theWeather Club Newsletter · the UK, ‘Wimbledon week’ saw a change to more warm and sunny conditions, with long, dry, settled spells and short interludes of exceptional warmth

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Autumn 2015:

Issue 11 Autumn 2015theWeather Club Newsletter

Weather Report Weather news stories from around the world during the last three months

Weather Watch

Societal applications of weather & climate

World Weather A traveller’s guide to the Philippines

Science Lesson Numerical Weather Prediction

And finally...Weather Facts

My Weather Dr Sam Illingworth talks about weather and poetry

Weather and Climate view

Paul Hardaker and Ellie Highwood comment on weather and climate

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Research News An update on recent scientific research

Weather Applications

A traditional manual weather station


www.theWeatherClub.org.uk2

Welcome The weather this summer was certainly a mixed bag for the UK, with both warm and sunny periods as well as very wet and cool stretches. In fact, daytime temperatures reached 36.7oC at Heathrow on 1st July - the hottest July day on record for the UK - whereas overnight temperatures fell to 1oC in Sennybridge, Wales on the last day of July.

Elsewhere in the world, we saw deadly heatwaves, damaging cyclones, floods and wildfires, whilst Eastern Australia experienced the most snowfall in years, with Melbourne having the coldest July since 1995.

In global terms, it was announced that the first half of 2015 was a record-breaker. Coincidentally, in July, 24 leading UK institutions released a Climate Communiqué calling for action on Climate Change ahead of the Paris Summit in November.

In this edition of tWC newsletter we explore Numerical Weather Prediction (NWP) in the Science Lesson (this year being the Met Office’s 50th anniversary of NWP), take a meteorological trip to the Philippines and delve into some weather poetry.

As we head into autumn, I wish you all a wonderfully crisp and colourful season!

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A Climate Communiqué

@RMetS

+ Weather Report

June 2015

1981 - 2010

Actual Anomaly

Average Max 17.2°C (-0.1°C)

Average Min 8.2°C (-0.6°C)

Mean Temp 12.6°C (-0.4°C)

Sunshine 196.2 hrs (116 %)

Rainfall 55.1 mm (75 %)

UK Weather

Dr Catherine L. Muller Author and Producer of theWeather Club Newsletter

In July, 24 UK leading institutions released a Climate Communiqué calling for immediate action to avert the serious threats posed by climate change.

The joint Climate Communiqué was initiated by the Royal Meteorological Society’s Climate Science Communication Group.

It says: “The scientific evidence is now overwhelming that the climate is warming and that human activity is largely responsible for this change through emissions of greenhouse gases.”

The one-page document was released ahead of the Paris summit in November 2015, where Governments will meet to negotiate a legally-binding and universal agreement on tackling climate change based on the latest scientific evidence.

The communiqué emphasises that in order to limit global warming to 2oC relative to the pre-industrial period, we must transition into a zero-carbon world early in the second half of the century. It also highlights and illustrates that governments must recognise the risks posed by climate change, embrace appropriate technological responses and seize opportunities for low-carbon and climate resilient growth.

This communiqué was launched at around the same time as data released from NOAA (US National Oceanic and Atmospheric Administration) showed that the first seven months of 2015 were the warmest since 1880, according to

globally-averaged land and sea surface temperature data. It is expected that 2015 will exceed 2014 as the warmest year in recorded history, especially if the El Niño (see p.12-13) continues to strengthen - indeed, it is already expected to rank among the top three such events on record.

The Communiqué can be downloaded from www.rmets.org/paris_climate_communique

Image: Climate Communiqué Infographic



A UK summer of extremes: hot and dry, cool and wetJune - August 2015

Weather ReportWhilst June saw dry, sunny, near-average temperatures for much of the UK, ‘Wimbledon week’ saw a change to more warm and sunny conditions, with long, dry, settled spells and short interludes of exceptional warmth during the start of July. Temperatures reached 36.7oC in Heathrow on 1st July, which the Met Office declared as the hottest July day on record, and temperatures widely peaked above 30oC. The heat also triggered thunderstorms and torrential downpours across parts of northern England and Scotland.

Although warm, sunny weather did continue to interlace summer, the weather became much more unsettled during late-July, seeing the return of rather prolonged wet and cool periods. In fact, on 26th July some parts of the UK even failed to reach the average temperature you would expect to find in October, whilst overnight temperatures in Sennybridge, Wales went down to 1oC on the last day of July!

Plumes of warm, moist air moving up from the near continent often triggers convective storms at this time of year. Although Scotland and Northern Ireland were mostly fine and dry, mid-August saw a wash-out further south in the UK. On 13th August, a month’s worth of rain (30-40mm) fell in just 9 hours in parts of the south-east, including Sussex, Essex and Kent. This lead to flooding which disrupted transport systems and inundated a shopping centre in Eastborne.

Late August saw the persistent wet weather continue, with a period of successive weather systems which brought wet and thundery weather to much of the UK. On the 24th August, more than a fortnight’s rain fell in some areas in just 24 hours and the bank holiday weekend was indistinguishable, albeit interspersed with some sunshine.

The Met Office have confirmed that overall, this summer was cooler and wetter than average but that sunshine totals were near-average for the UK.

July 2015

1981 - 2010

Actual Anomaly

Average Max 18.5°C (-0.8°C)

Average Min 10.3°C (-0.6°C)

Mean Temp 14.4°C (-0.7°C)

Sunshine 164.8hrs (96%)

Rainfall 109.5mm (140%)

Northern Hemisphere heatwaves

Whilst the UK avoided extended periods of significantly hot weather this summer, other parts of the Northern Hemisphere suffered prolonged and devastating heatwaves.

Closer to home, much of the southern Mediterranean – particularly Spain, Portugal, France and Germany - experienced temperatures in the 40s during late June and July, triggering health and forest fire alerts across the region. The Spanish cities of Cordoba, Seville and Toledo were some of the worst affected with temperatures up to 44oC in some areas in late June. Germany registered a new all-time temperature record of 40.3oC.

India, Pakistan and the Middle East also suffered deadly heatwaves. In southern Pakistan, more than 65,000 people were

taken ill and more than 1,200 people died from heatstroke as temperatures climbed well over 40oC for extended periods, in what has been one of the most sustained heatwaves in the country since records began.

Parts of the Middle East also suffered a number of prolonged heatwaves through spring and summer, with the mercury creeping well into the 40s at times, igniting fires that damaged homes and infrastructure.

In fact, on 31st July, air temperature in the city of Bandar Mahshahr in Iran reached 46oC, and the heat index (the temperature it actually ‘feels like’) peaked at an astonishing 74oC – potentially one of the highest levels ever experienced, though there are no official records of heat index.

UK Weather

June - July 2015

Images: (top) ECMWF model of high temperatures on 2nd July, (bottom) Flooding on 13th August.



+Weather Report

August 2015 marked the 10-year anniversary of Hurricane Katrina, the most costly hurricane on record causing an estimated $108 billion in damage in Louisiana and Mississippi and an estimated 1,500 deaths. However, this year the Atlantic Ocean is experiencing a relatively quiet hurricane season. The Pacific Ocean typhoon season, on the other hand, has been very active, particularly from late June onwards. It is forecast to be the most active since 2004. A strong El Niño tends to promote tropical cyclone activity in the Pacific whilst suppressing it in the Atlantic.

In early July, three tropical cyclones - Severe Tropical Storm Linfa, Typhoon Chan-hom and Typhoon Nangka - formed almost simultaneously. Chan-Hom became the strongest storm to make landfall in the Zhejiang province since 1949.

At the end of July and early August, Typhoon Soudelor became the strongest storm so far, reaching peak intensity with winds of 130mph (with one-minute sustained winds of 180mph recorded) and an atmospheric pressure of 900hPa on 3rd August, making it a Category 5-equivalent super typhoon at its peak. It brought chaos to Taiwan and parts of south-eastern China in early August, bringing rains and gale force winds which triggered landslides, leaving at least 14 dead and millions of homes without power. One coastal area saw more than 50cm of rain in 24 hours – the heaviest for a century.

US wildfires - a monster season

Active Pacific typhoon season

August 2015

1981 - 2010

Actual Anomaly

Average Max 18.8 °C (-0.3 °C)

Average Min 10.7 °C (-0.1°C)

Mean Temp 14.7 °C (-0.2°C)

Sunshine 154.3 hrs (95%)

Rainfall 107.4mm (120%)

UK Weather

June - August 2015

July - August 2015

An explosion of wildfires has occurred across the west coast of the United States, including Washington, Montana, Oregon, Idaho and California - Washington State experienced the largest fire in its history. Many residents were forced to flee their homes and a number of people lost their lives. One blaze, the Soda Fire near Nampa in south-west Idaho, burned 265,000 acres, becoming the largest blaze in the nation.

Many fires were sparked by lightning strikes and fuelled by severe drought - now into its 4th year for this part of the US. These are exacerbated by strong winds, which are posing problems for fire fighters trying to contain the flames. Indeed, emergency workers from Australia and New Zealand were deployed to the US to assist with the fire fighting. The US Forest Service is currently spending about $100m a week fighting the wildfires.

The elevated risk of wildfires in this part of the world is not unusual in summer due to

Image: Trio of category 4 hurricanes over Pacific Ocean (Source: National Aeronautics and Space Administration (NASA))

Image: Firefighters tackle wildfires in Washington State

In mid-August, twin typhoons Goni (category 3) and Atsani (category 1) became the ninth and tenth typhoons of the year. Goni lashed the Philippines and southern Japan, reportedly killing at least 19, whilst Atsani tracked towards Japan, before weakening to a tropical storm.

However, as we left the summer season, all eyes were on the trio of category 4 hurricanes that churned in the Pacific Ocean. Hurricanes Kilo, Ignacio and Jimena stirred simultaneously on 29th August, which was the first time in recorded history that three hurricanes of such strength had existed at the same time in the Pacific Ocean.

hot and dry weather, but so far 2015 has seen 43,819 fires which has charred 8,202,557 acres - over two million more than 10-year average.

A NASA analysis of 35 years of meteorological data found that many western parts of the US face longer wildfire seasons than they did a few decades ago, a likely impact of climate change.



US wildfires - a monster season What impact would a ‘grand solar minimum’ have on our future climate?

Is Asian air pollution changing US weather patterns?

Research News

Research published in the Proceedings of the National Academy of Sciences suggests that air pollution from China and other Asian countries is having far-reaching impacts in weather patterns across the Northern Hemisphere.

Parts of Asia have some of the highest levels of air pollution, with some cities frequently exceeding levels recommended by the World Health Organisation. Tiny particles - produced from the burning of coal in power plants or traffic emissions, for example - can hitch-hike on the jet stream and are blown towards the north Pacific. Water vapour in the atmosphere condenses around these particles (known as ‘cloud condensation nuclei’), with large amounts of particulate matter producing larger, deeper clouds that can cause intense storms above the ocean.

This study – conducted by researchers from NASA’s Jet Propulsion Laboratory – used computer models to look at the effect of Asia’s air pollution on weather systems, finding that the pollutants are strengthening storms above the Pacific Ocean, which subsequently feeds into weather systems in other parts of the world, particulary in winter.

A paper, led by Met Office scientists in collaboration with the universities of Cambridge, Oxford, Reading and Colorado and published in Nature Communications, has explored the potential regional impacts of a drop to solar activity not seen in centuries. The study found that the return of a ‘grand solar minimum’ not seen in centuries could increase the chances of cold winters in Europe and eastern US, whilst failing to halt global warming.

Variability in the sun’s output is measured by the number of sunspots on its surface, over a period of 100-200 years. Some solar physicists believe there is an increased risk that we are heading towards the minimum stage of this solar cycle – last seen during the so-called ‘Maunder Minimum’ which ended 300 years ago and coincided with colder winters in UK and Europe.

Climate scientists have been investigating the impact this would have on global temperatures using a climate model to simulate conditions from 2050 to 2099, implementing the Representative Concentration Pathways (RCP) 8.5 scenario (a socio-economic scenario which assumes ‘high-end’ future carbon concentrations) and reducing solar output to Maunder Minimum levels.

The findings from this study indicate that the global impact from decreased solar output was relatively low (a cooling effect of around -0.1oC), and much smaller than the amount of warming expected as a result of greenhouse gases (several degrees for this particular experiment).

Lead author Dr Yuan Wang, from the Jet Propulsion Laboratory at the California Institute of Technology, said: “The effects are quite dramatic. The pollution results in thicker and taller clouds and heavier precipitation.”

“Since the Pacific storm track is an important component in the global general circulation, the impacts of Asian pollution on the storm track tend to affect the weather patterns of other parts of the world during the wintertime, especially a downstream region [of the track] like North America.”

Commenting on the study, Professor Ellie Highwood, a climate physicist at the University of Reading (and tWC contributor – p.13), said: “We are becoming increasingly aware that pollution in the atmosphere can have an impact both locally - wherever it is sitting over regions - and it can have a remote impact in other parts of the world. This is a good example of that.”

“There have also been suggestions that aerosols over the North Atlantic effect storms over the North Atlantic, and that aerosols in the monsoon region over South Asia can affect circulation around the whole of the world.”

Regionally, a larger cooling effect was found for northern Europe, the UK and eastern parts of North America, especially in winter, with northern Europe experiencing a mean drop in temperature in the range -0.4oC to -0.8oC. Although globally-speaking, winters at that time are projected to be warmer overall, this work suggests an increase in the risk of colder winters during a grand solar minumum.

The impact of a grand solar minimum would, therefore, only temporarily moderate future warming from climate change.

Sarah Ineson, a Met Office scientist and lead author of the research, said, “This research shows that the regional impacts of a grand solar minimum are likely to be larger than the global effect, but it’s still nowhere near big enough to override the expected global warming trend due to man-made change. This means that even if we were to see a return to levels of solar activity not seen since the Maunder Minimum, our winters would likely still be getting milder overall.”

“This study shows that the sun isn’t going to save us from global warming, but it could have impacts at a regional level that should be factored in to decisions about adapting to climate change for the decades to come.”

Amanda Maycock, a scientist at the University of Cambridge and National Centre for Atmospheric Science, added: “Given the outlook for solar activity from some experts, it’s important that we consider the potential impact of changes in Ultraviolet (UV) output when looking at future climate.”



+Weather Applications

Weather information is vital for a range of industries, services and societal applications - from transportation infrastructure to retail industries - with some uses more obvious than others. Here we take a brief look at some of these applications.

• Transport: Flooding can cause chaos within most transportation networks, but extreme heat, cold weather and high winds also wreak havoc: buckling rails, melting asphalt, leaves on the line, felled trees, ice and snowfall, to name a few. Transportation networks have an obvious need for regular weather forecasts and updates (i.e. for informing gritting routes, speed restrictions etc), but long-term, they also require an understanding of the impact of a warming world and changing climates upon infrastructure.

• Aviation: From nowcasting weather hazards to the monitoring of volcanic ash, weather information is vital to all sectors (airlines, airports, air traffic control, ground handling, construction and maintenance) in order that correct and timely decisions are implemented, to maintain safety and keep to schedules.

• Sailing: Shipping forecast and gale warnings are vital for planning routes and to ensure appropriate responses are made to changing conditions during a trip.

• Health: Heatstroke, cardiovascular diseases, cold-related illnesses are all caused or exacerbated by certain types of weather. Health professionals in hospitals, surgeries and emergency services need to be aware of impending weather events that will have an impact on health in order to predict and plan for likely outcomes.

• Retail: Changeable weather impacts on retailers, who can lose millions in revenue if stocks are too low, or conversely too high. For example, hot weather sees a rise in demand for items such as bbq food, ice cream etc, and decrease in demand for ‘hearty’ foodstuffs. Similarly, demand for umbrellas increases during periods of heavy or persistent rainfall, whilst demand for gloves and scarves increase during cold-snaps. Understanding the impact different weather events have on the retail market in conjunction with weather forecasts can therefore have a huge impact on profit margins. In fact, weather is estimated to cost the fashion industry £700 million, with prolonged periods of bad weather having the worst impact.

• Utilities: From heatwaves and droughts to flooding and cold snaps, weather and climate impacts both supply and demand of gas, electricity, water, renewable energy (e.g. wind, solar), waste and even Information and Communications Technology (ICT) Utility companies therefore need to be aware of predicted weather conditions in order to forecast short-term supply and demand. Climate projections are also vital for managing longer-term risks, whilst historical climate information is utilised in renewable energy planning.

• Agriculture: Weather and climate information is vital for advising on the suitability and planting of crops, irrigation needs, alerts for pests and diseases and other farming requirements.

• Sport and Leisure: A huge industry in which weather plays a major part. Outdoor events such as football, motor sports, horse racing, cricket, tennis, music festivals etc rely heavily on weather forecasts in terms of safety, financial imlications and other practicalities.

• Mining: Weather and climate information goes into site-specific plans and risk assessments as part of initial the planning process.

• Building and Construction: From the use of weather and climate averages for the build location during the initial stages of the project planning to specialised forecasts during the implementation of sustainable housing in future climates.

• Finance and Insurance: Extreme weather events are expected to increase in frequency as the climate changes, so it is vitally important that insurance companies, reinsurance companies, traders and brokers understand these risks, as well as both short-term forecasts and historical information about natural hazards (such as windstorms, floods).

• Planning and Management: Weather and climate risk assessments and advice needed during planning and management of a wide variety of projects.

• Tourism: Whether people are going abroad or staying at home, anyone involved in the tourism industry is affected by weather. If a heatwave is forecast in the UK, more people tend to remain at home rather than travel abroad; if a wash-out summer is predicted, sales of international holidays will increase. Tour operators, airlines and local service providers (i.e. hotels, shops, restaurants) can use such information to plan or respond accordingly.

In future issues of tWC we will explore seasonal case studies of how weather and climate can have an impact on specific industries and various aspects of society.

Societal applications of weather and climate information



+Weather Watch

Recent articles in this series have discussed setting up an automatic weather station and how you can use it to display continuously-updated observations from your back garden on the web. But many budding amateur meteorologists (or schools) may be looking for something less high-tech, so in this article we look at a weather station made up of simple manual instruments.

A full weather station will generally measure temperature (including maximum and minimum), humidity, rainfall, wind speed, wind direction, pressure and perhaps also solar radiation. All of the observations, with the exception of pressure, need to be made outdoors, and the great advantage of manual observation is that you get to immerse yourself in real weather, and learn to associate measurements with how it feels. More detail on the available choices of instruments needed to make these observations have been covered in previous editions of the newsletter; here we take a typical sample, with illustrations above.

Instruments for measuring temperature and humidity have to be sheltered from the sun; if sunshine falls on a thermometer it will heat it up and so will measure its own temperature rather than that of the air around it. This is done using a box called a screen which shades the instruments from the sun but allows air to pass freely over them because the sides are louvred. These often go under the generic name of Stevenson screens (after their inventor,

the father of Robert Louis Stevenson), but in fact come in many different shapes and sizes (and prices). A good starting point for amateurs is shown in the picture below; it will hold (for example) a maximum-minimum thermometer (£10, which also, of course, reads current temperature) and a wet-and-dry-bulb hygrometer (£15) for measuring humidity. The screen costs about £90 ready-built; alternatively a kit to be assembled and painted will be about £50. In strong sunlight and light winds temperatures inside can still read too high by a few degrees; bigger screens with smaller errors (like the ones used by the Met Office) cost up to £600.

A basic rain gauge, made of plastic but using the same construction as Met Office rain gauges, costs about £15. It is simply fixed at ground level and rainfall amount is measured by pouring the rain from the funnelled collector into a measuring cylinder every morning. The most economical way of measuring wind speed is to use a propeller anemometer (£10), which needs to be held at arm’s length and as high as possible, and pointed into the wind. Wind direction can be judged

Geoff Jenkins describes a typical traditional low-tech manual weather station

using a flag or a simple wind sock (£1) on as tall a pole as possible. Finally, if you haven’t already got a barometer in the hallway, a simple one with a clear scale in millibars (now renamed hectopascals) will set you back about £15-£20.

As with automatic weather stations, the best measurements are made in good open conditions, of the sort not often available to back-garden amateurs. But that doesn’t matter too much, as any measurements you make will be interesting, and will represent your local microclimate. If you have (as I and 70% of the population have) a pocket-handkerchief back garden on a housing estate, then it will also represent the climate of most of the people in the neighbourhood.

The total cost of all the instruments and self-assembly screen shown above will total about £130 including VAT, if bought online. But of course you don’t have to measure everything, and certainly not all at once – by dropping subtle hints a complete station can be built up over a couple of years from a succession of birthday and Christmas presents!

Setting up a simple weather station

Simple instruments for a manual weather station. Clockwise from top left: humidity and max-min temperature (both mounted in a screen), rainfall (plastic rain collector and measuring cylinder), wind speed (propeller an-

emometer), wind direction (wind sock on a bamboo pole) and pressure (aneroid barometer).



+WorldWeather

The Philippines is defined by its lush rice fields, chocolate hills, smouldering volcanoes, wide-eyed tarsiers and breath-taking sunsets. Its bustling megacities with ‘dancing traffic cops’ and graffiti-splashed jeepneys, are home to some of the warmest people on Earth. With more than 7,000 islands, the Philippines is a traveller’s delight with, it seems, and island to suit every taste, from marooned slicks of sand in the middle of the ocean to sprawling mega-islands such as Luzon, containing the capital city, Manila.

Whilst torrential monsoon rains and cyclones affect many parts of this region,

the Philippines does, in fact, have four distinct climates.

The first type of climate has two pronounced seasons: dry November to April and wet May to October. This climate is found along western fringes, from Palawan and Mindoro up to Luzon and including Manila. These western parts receive heavy rain at the peak of the southwest monsoon (July to September).

Palawan, often cited as the Philippines’ last ecological frontier, is the country’s most sparsely populated region. Southern Palawan has rugged

A traveller’s guide to the Philippines

A map of Philippines (Source: www.

graphatlas.com/)

topography and jungle-clad mountains, whilst the north is more developed, yet still retains a very rural feel. Indeed, its capital, Puerto Princesa is aptly nicknamed ‘the city in a forest’ since it blends in with its surrounding rather than replacing it. El Nido is a popular tourist destination in north-western Palawan, consisting of numerous small islands – the Baracuit archipelago is perfect for island-hoping on a banka (local boat). The Calamian Islands lie to the north of Palawan and are famed for some of the world’s best diving spots. Just to the north lies Mindoro, home to the ‘High Rolling Mountains’ which separate the island’s two provinces:

Image: A map showing the different climate of the Philippines



rough and rugged Mindoro Occidental to the west, and more prosperous Mindoro Oriental to the east.

Heading north from Mindoro will eventually land you in Manila, the capital city. Manila – the ‘Pearl of the Orient’ – is a bustling megacity which has endured every disaster both human and nature could throw at it. Like all megacities, on the surface it comprises of skyscrapers, congestion and visible inequality, yet these typical urban features conceal its edgy bars, artisan markets, and historic centres.

The second climate type found in the Philippines describes regions that have no distinct dry season but are wet throughout the year, with very pronounced rainfall from November to April. This climate is experienced along eastern regions, from north-east Mindanao up through Samar to south-east Luzon and the Polillo islands. Eastern Samar, Luzon and the central Visayas bore the brunt of Super Typhoon Haiyan in November 2013 (see information box above).

A third type of climate is found mostly in the central regions of the country, including many parts of the Visayas and central Mindanao, but also south eastern Palawan. Seasons are not very

pronounced but it is relatively dry from November to April, and wet during the rest of the year.

The Visayas are a group of Islands lying in central Philippines: Cebu is home to the Philippines second city, Cebu City; Negros is known for its soft, super-sweet mangos; Panay is the place sun-worshippers head to for the famous beach town of Boracay.

All other parts lying in-between regions with type 2 and 3 climates - from the very southern parts of Mindanao, through Bohol and Leyte up to the north-eastern parts of Luzon – experience similar levels of rainfall throughout the year, and define fourth climate type.

Climate of Manilla, Philippines

Average min temperature range: 21°C in January to 25°C in June

Average max temperature range:30°C in December to 35°C in April

Average driest month: January with 20mm and 6 rain days

Average wettest month: August with 431mm and 24 rain days

Average daily sunshine: 5 hours in January to 9 hours in April

Image above: Chocolate Hills, Bohol

Image above: Filipino sunsetImage above: El Nido, Palawan

Super Typhoon Haiyan Cyclones can affect any part of the Philippines, depending on the path the cyclone takes. Super Typhoon Haiyan (known locally as Yolanda) cut a path across central Philippines, making landfall on 8th November 2013. In the north-west Pacific a tropical cyclone is classified as a Super Typhoon when its winds are greater than 150 mph. The strongest reported wind speeds associated with Haiyan reached 195 mph, making Haiyan the strongest tropical cyclone to make landfall on record and the fourth most intense tropical cyclone ever observed. Haiyan caused catastrophic destruction in the central area, particularly on Samar Island and Leyte. According to the UN, about 11 million people were affected. Natural disasters are not uncommon in the Philippines and the local people are resilient, but the scale of damage caused by Super Typhoon Haiyan was unprecedented.

Image above: Super Typhoon Haiyan

Bohol is famed for its Chocolate Hills, some 1,200 symmetrical mounds that turn cocoa-brown during drier periods. It is also home to tarsiers, small, wide-eyes primates, and stunning white beaches and coral reefs.

Whatever time of the year it is, there’s a region of the Philippines that has something special to offer and it is truly worth visiting this still relatively undiscovered travel destination before the secret gets out! But of course, if you are planning a trip, do keep an eye on typhoon warnings and other natural disasters, by visiting the Pacific Disaster Centre (www.pdc.org).



+ScienceLesson

Shall I walk or drive to work this morning? Should I take my umbrella with me today? Will the school be closed due to snow tomorrow? Weather permeates all aspects of our lives – but forecasting the future is no mean feat. This year is the 50th anniversary of Numerical Weather Prediction (NWP) in the UK, so we thought we’d take a look at this essential tool in this edition’s Science Lesson.

NWP is forecasting weather by computer using the laws of physics, and it is the cornerstone of modern forecasting. The essential ingredients of NWP were articulated by American Cleveland Abbe in 1901 and Norwegian Vilhelm Bjerknes in 1904. They wrote that the future motions of the atmosphere could be predicted – just as the motion of a pendulum or a ball thrown in the air could be predicted – by knowing two things: the current weather and the physical laws that govern the atmosphere.

1. The current weather: Imagine taking a snapshot of the current atmospheric conditions around the world (temperature, precipitation, pressure, etc, not only at the surface of the Earth, but above the Earth as well). These observations are collected from surface stations, instrumented weather balloons, satellites, and instrumented commercial aircraft. When combined, they produce that snapshot, or what we call the initial conditions.

2. The physical laws: Five simple laws can be written as mathematical equations. These mathematical equations describe how the pressure, temperature, moisture, and winds change with time, as well as describe the relationship between temperature, density, and pressure of air (also known as the ideal gas law).

These current weather conditions and physical laws are put into a form that computers can understand. It takes thousands of lines of computer code to represent these five simple laws. When the computer code is started from the current weather, the computer generates output (i.e. data on hundreds of meteorological elements at different heights throughout the atmosphere), which represents the projections of the weather for the future.

Given the simplicity of this process, you might think that the weather predictions would be perfect. But, these same two ingredients can be used to show that weather predictions are never perfect.

Consider the current weather. Observations are collected mostly where people live. Over the oceans, few surface observations of the current weather are collected. Observations from weather balloons are even more sparse. Satellites have global coverage, but often cannot take the measurements needed for NWP. So, we lack good information about the present weather over large expanses of the globe. Less-than-perfect initial conditions means that the

Numerical Weather Prediction (NWP)quality of the forecast can sometimes suffer. Scientists are working to increase the amount of useful data and create better initial conditions for the computer models to improve the forecasts.

Forecasts can also go wrong because of the computer model. Limited by the available computer power and the need to produce a 12-hour forecast in less than 12 hours means that shortcuts are needed in the computer code. Imperfect knowledge of how some important physical processes happen (such as the interaction between sunlight and clouds or how heat and moisture are transferred from the ocean surface to the atmosphere) can lead to a less-than-perfect model, which in turn lead to less-than-perfect forecasts. Scientists are working on developing improved understanding of poorly understood physical processes, and computer scientists continue to develop more accurate and faster numerical

Image: The 30h WRF forecast for 0000 UTC 5 February 2014 on the domain with 20km horizontal grid spacing: mean sea-level pressure, 10m wind speed, and simulated maximum radar reflectivity. The solid lines for mean sea-level pressure values appear grey because of the

semi-transparency of the other quantities plotted.



algorithms and models to improve forecasts.

The third reason why otherwise good forecasts can be imperfect is called chaos theory or the butterfly effect. Even if we had perfect initial conditions and a perfect model, the weather forecast would never be faultless. Small unobserved perturbations (such as the flap of a butterfly’s wing) has been said to be enough to change the weather forecasts days in the future. Even the rounding errors in the computer code could be enough to produce different forecasts from the same initial conditions.

So, given all these reasons that limit our ability to make the perfect weather forecast, the fact that we still get reasonable forecasts for large-scale weather patterns several days in advance is a testament to how we have overcome these severe limitations and make predictions of the future. The weather forecasts are never flawless, but they are certainly useful. What other discipline can boast such useful forecasts of the future, especially when compared to the challenge of the highly chaotic atmosphere?

NWP forms the basis of the weather forecasts we receive through mediums such as the

Applications Case Study: ManUniCast - a real-time weather and air-quality forecasting portal and appForecasts of air chemistry and air quality are even more challenging than weather forecasting: not only does the weather need to be well predicted, but the chemical reactions occurring amongst the atmospheric gases and on the water and ice particles in the clouds need to be understood and incorporated into the models. All chemicals and chemical reactions occurring in the atmosphere need equations describing how they change over time. Even the most basic chemistry models for the atmosphere have tens of chemicals and thousands of chemical reactions, and hence thousands of equations. Not only do models have to include all these chemical reactions, but they also need initial conditions including the concentration of trace gases, size and composition of solid aerosol particles suspended in the air, and the emission of pollutants. These initial conditions are less well-known than for weather.

ManUniCast is a real-time and archived weather and air-quality modelling system, web-based portal and mobile app. It provides real-time weather and air quality forecasts made by a state-of-the-art model free to students and the general public. ManUniCast was designed as a tool for teaching rather than an operational forecasting system. It begins with a

until the era of computers in the late 1940s. The ENIAC (Electronic Numerical Integrator And Computer), the first electronic general-purpose computer, was used to create the first computerised weather forecasts in 1950. Operational weather prediction began in 1955 in the US under the Joint Numerical Weather Prediction Unit, whilst in the UK, the Met Office launched its first operational NWP system in November 1965. 2015 marks the 50th anniversary of this launch. A meeting will be held at the Met Office to celebrate the history and look to the future of NWP. More information can be found at: www.rmets.org/events/met-office-50th-anniversary-numerical-weather-prediction-nwp.

Since this time, models have continued to develop in complexity as our understanding of the atmosphere improves and computing power increases, resulting in increasingly accurate weather forecasts. Indeed, today’s three-day weather forecasts for the UK are more accurate than a one-day forecast was in 1980 - progress indeed!

[Co-authored by Prof. David Schultz, Professor of Synoptic Meteorology, University of Manchester]

TV, radio, websites and smart apps. For a forecast to be useful to the end user, it must be understood. Meteorologists and weather presenters interpret the output that is produced by the NWP and, using their specialist knowledge, turn this data and information into a weather forecast that can be communicated to, and understood by, the end user (i.e. the general public, industries (see page 6).

History

Attempts to forecast the weather were made as far back as 650 BC in Babylonia, but the development of accurate meteorological instruments during the 1800s paved the way for modern meteorology. Until as recently as the early 1900s, weather prediction was taken no less seriously than soothsaying. When Abbe and Bjerknes first suggested that the weather could be predicted using physical laws, they also recognised that humans would take too long to perform the calculations by hand. Indeed, Yorkshireman Lewis Fry Richardson hand-calculated a single 6-hour forecast over Europe in a procedure that took many months! This difficult, time-consuming approach meant that practical forecasts were not possible

set of initial conditions from the coarsely-gridded (20km) Global Forecasting System (GFS) global model run by the NOAA National Weather Service of the United States. Small-scale details are not captured in this analysis, so it may sometimes miss important weather phenomena.

The UK region in ManUniCast is constructed from grid points spaced 4km apart. Although this is quite detailed, the ManUniCast forecasts may not develop the weather in the right place at the right time, particularly for convective storms. Users of this data therefore need to recognise these limitations. On the other hand, large-scale weather patterns such as low-pressure systems, high-pressure systems, and fronts, will usually be forecast well within the 54-hour forecast period of ManUniCast.

ManUniCast links: www.manunicast.com

https://itunes.apple.com/gb/app/manunicast-weather-air-quality/id905281887?mt=8

Images: Screenshots from the ManUniCast app viewed on an iPhone.



+Weather View Prof Paul Hardaker

Chief Executive ofThe Institute of Physics

I was always fascinated at school by the Trade Winds, mainly because I didn’t understand how they could blow from east to west (easterlies) when the planet rotated west to east, surely the wind would follow the rotation of the earth. I later found out that George Hadley, an English meteorologist, had been thinking about the same thing when he wrote about this in 1735, and something that became known as the Hadley cell. Here air rises at the equator and moves at high levels from the equator towards the pole where it cools and sinks in the sub tropics in the high pressure belt. It turns out the reason it returns towards the equator with an easterly flow is because of the Coriolis effect. I’ll leave you to work out why this effect turns the wind to the right of its direction in the northern hemisphere. You’ll need an old CD and a marker pen to convince yourself of this. I first did it with an old 7-inch 45 rpm record (you might need to look up what that is if you’re under 40!).

Easterly winds in general get a bad rap, which is undeserved in my view. Eurus, the Greek god of the east wind was said to be unlucky. Sir Arthur Conan Doyle used the east wind as a reference to the return of Professor Moriarty, and Tolkien wrote about it as “a thing of evil”. Even Dickens’ Mr Jarndyce, in Bleak House, thought of it as “a harbinger of unfavourable events”. I’m sure you don’t see those literary references together in one paragraph very often.

But explorers like Christopher Columbus and Ferdinand Magellan knew about the value of the easterly Trade Winds. The Manila galleons, popular sailing vessels at the time, could not sail into the wind and so had to use the Trade Winds to cross from Europe to the Americas, establishing early trade routes (hence the name). Later ships like the Cutty Sark tea clipper with specially strengthened masts would make these journeys in record time.

What I did learn a little about at school was the important impact the Trade Winds have on the weather. However what we didn’t know in those days is the connection between the Trade Winds and the development of El Niño. We hear a lot about El Niño these days,

but what is it? Well, El Niño is a warming of the southern Pacific off the coast of South America. Peruvian Naval Captain Camilo Carrillo reported to the geographical society congress in Lima in 1892 that the warming was first spotted by Peruvian fisherman. Because the warming was strongest around the turn of the year they christened it El Niño, Spanish for Christ Child. Although it doesn’t get as much media attention, there is also an opposite cold phase called, you might have guessed it, La Niña.

Scientists often call this something different, and it goes back to one of our great 20th century physicists Sir Gilbert Walker. In 1923 Walker noticed a seesawing (for want of a better description) of atmospheric pressure between the Pacific and Indian oceans, and he called this the Southern Oscillation. By the 1980s it had become clear that there was a very strong relationship between occurrences of this Southern Oscillation and both El Niño and La Niña, and so scientists began to call this the El Niño – Southern Oscillation, or ENSO for short.

So what is this association with ENSO and the Trade Winds? Well the Trade Winds usually push the warm water west towards Asia and allow an upwelling of cold water in the eastern Pacific. But when the pressure gradient across the Pacific weakens then so do the Trade Winds and this allows the warmer water to move eastward. You can imagine that having a very large nose of warm water stretching out across the

southern Pacific can have a big impact on global weather systems.

There is lots of evidence that El Niño has had an impact on many communities and cultures through time: the demise of the pre-Columbian Incas; poor crop yields in the late 1700s which helped to trigger the French Revolution; the 1876 famine which killed 13 million people in China; numerous droughts in India and Australia; and the list goes on. Then came the El Niño events of 1982/3 and 1997/8, the first major events were we had the technology to properly observe them, and of course it captured everyone’s interest.

The 1997/8 event was so large, with more energy than a million times the Little Boy atomic bomb dropped on Hiroshima (that’s 1018 Joules), it temporarily warmed the air temperature by 1.5oC, about three times that of an average El Niño event. The impact on global weather was striking. It was reportedly responsible for the deaths of an estimated 2,100 people, it caused at least $33 billion in damage, and it is estimated that some 16% of the world’s reef systems died as a result of the warmer ocean waters.

But what of El Niño over recent years? Well, during the last 40 years we believe there have been nine discernable El Niño events. Since 2000, El Niño events were observed in 2002/3, 2004/5, 2006/7 and 2009/10, but an El Niño as strong as the one observed in 1997/8 has not been seen since. Observations from the tropical Pacific, earlier this year, show that we have moved to weak El Niño conditions for the first time in five years.

We can now not only observe the onset of El Niño conditions, which give us some advanced notice, but we are also able to make predictions. They are not anywhere near as accurate yet as weather forecasts, but without these advances we cannot hope to make sensible seasonal forecasts or decadal predictions of the climate. All of this demonstrates that it is sometimes better to have stronger, rather than weaker easterlies, as long as it is in the right part of the global circulation!

When the east wind rose with greater force, ‘twere wise to change my course

Because the warming was strongest around

the turn of the year they christened it

El Niño, Spanish for Christ Child.



+ClimateView

Prof Ellie HighwoodProfessor of ClimatePhysics at theUniversity of Reading

The wonderful world of teleconnections: why everyone should care about El NiñoOne of the most intriguing things about the climate system is how temperature and rainfall in one part of the world can be influenced profoundly by things going on thousands of kilometres away. The atmosphere is a global system – there are no intercontinental barriers as such and moisture and energy can flow more or less freely, albeit with preferred patterns. Most people will be familiar with the broad climatic zones; warm wet tropics, warm dry subtropics or arid belts of latitude, cooler and wetter mid-latitudes, and the cold polar regions. On large scales and through the depth of the troposphere, air tends to rise in the tropics and mid latitudes and descend in the arid zones. These patterns are modified by weather systems moving across the planet, and by other circulations that operate from east to west or west to east rather than north to south. When parts of these circulation systems are disrupted, the effects can be felt at a great distance and we call the links between source and receptor regions “teleconnections”.

Since early 2015, one of the important east to west tropical circulations has been in a phase where the convection and ascent of air has moved from the west Pacific to further east, following the movement of warm sea surface temperatures into the eastern Pacific. This phenomenon is referred to as El Niño and to some degree happens every 3 to 4 years, but with differing “strengths” as determined by the change in sea surface temperature in the Pacific. In July 2015, tropical Pacific temperatures were 1.2°C warmer than usual and the ocean-atmosphere coupling was kicking in strongly weakening easterly winds at the surface and westerly winds aloft, with more clouds in the central and Eastern Pacific than normal. The weakening

winds at the surface allow more warming of the water which suggests that El Niño will continue to strengthen through the autumn. NOAA predictions suggest 3 month average Pacific temperatures in late autumn, early winter of around 2°C which would place this El Niño as one of the stronger ones on record (since 1950) and approaching the levels of the 1998 event.

During previous strong El Niño events, the atmospheric teleconnections produce effects across the globe. Changes to the pattern of rising and sinking air cause changes in the pattern of clouds and rainfall. In general the Hadley circulation (air rising at the equator

and moving at high levels towards the pole where it cools and sinks in the sub tropical high pressure belt) is invigorated and leads to knock-on effects on weather patterns elsewhere. For example, the warmer and more buoyant air in the central and east Pacific moves northwards and pushes the North Pacific jet stream further south and east than normal. This can result in more stormy weather and indeed excess rainfall in the southern US is one of the more reliable effects of El Niño. Other often seen effects of these teleconnections to remote regions are less than normal rainfall over Indonesia, Australia and the Sahel in Africa as well as northern South America and excess rainfall in eastern Equatorial Africa. Following from this can be drought, floods, heatwaves and other societally important effects. El Niño is one of the most important manifestations of natural variability in the climate system.

A natural question then is whether El Niño frequency or strength, or indeed its side effects are likely to change in a world affected by greenhouse gas induced warming. Historically, climate models have found it difficult to simulate ENSO. Some of the most recent climate models show an improvement in El Niño amplitude and those that simulate strong El Niño’s well, also simulate a gradual increase in El Niño intensity. Since the moisture availability increases in a warmer world, several models suggest that ENSO related rainfall variability in some regions will intensify. Some models also suggest that the teleconnection patterns may shift further east over the North Pacific and North America. However, future changes are very model dependent and therefore uncertain.

When parts of these circulation

systems are disrupted, the

effects can be felt at a great distance

and we call the links between

source and receptor regions

“teleconnections”.



+My Weather

Weather has always formed an integral part of my research career, as an atmospheric physicist I analysed meteorological data from weather satellites, forecast conditions prior to aircraft campaigns, and even sang songs to primary school children about the water cycle. Now, as a lecturer in science communication, my research is focussed on trying to better understand and develop the connections between science and society. The weather is a fascinating example of a topic that has its feet firmly in both camps, being something that most people talk about on a daily basis, whilst also being the topic of substantial scientific study.

Given the unique position that the weather occupies in the lives of so many of us, it is an ideal topic for genuine two-way dialogue between scientists and non-scientists to take place. The scientists would no doubt benefit greatly from the wealth of experience on offer from weather enthusiasts, whilst hopefully being able to offer further insight into topics such as weather satellites and climate modelling.

One of the ways in which I try to connect science and society is by writing poetry about recent scientific studies. I write my poems to act as a conduit between researchers and the general public, communicating the crux of the scientific studies in an accessible and hopefully enjoyable manner. As an exemplar, this is a Shakespearian Sonnet, which I wrote about some recent research investigating the effect that jet contrails have on land temperature:

The Poetry of WeatherSam Illingworth is a lecturer in Science Communication at Manchester Metropolitan University in the UK. His research involves looking at the ways in which science interacts with society via different cultural media. When he is not doing that he likes to write bad poems about good science, some of which can be read here. Feel free to email him at [email protected] or Tweet him anytime at @samillingworth.

Contrails cast shadows across azure skies,As jet exhausts do freeze in cold, moist air.

But we have just begun to realiseThe great effects of what happens up there.

By studying two sites that were the same,Apart from the presence of those white streaks,Research has shown the shadows are to blame

For less range in diurnal troughs and peaks.

They found the temperature of land belowHad decreased max and elevated min;A six-degree reduction they did show,

With Fahrenheit the unit they worked in.

Next time you see the sky criss-crossed in white,Think what this means for those beneath the flight.

Contrails



As well as being a scientist, I am also an Englishman, and as such I often find myself preoccupied by the rain on a purely superficial level. Will it rain today? If so, how much? Will I need an umbrella? Should I wear a waterproof coat or a lighter jacket? Should I put the washing out now, or get up early and do it tomorrow? Despite the large amount of time that I spend thinking about the rain, I don’t think that it is reciprocated, as demonstrated in this Kyrielle, which I have written especially for My Weather.

Despite its apathy towards us, the weather is a fascinating topic, and like a jilted lover I will continue to write about it in this fashion. I hope that the weather’s other jilted lovers, be they researchers, enthusiasts or experts can unite and share their stories, as doing so makes for a far more rewarding experience.

To read more of Sam’s poetry, visit:thepoetryofscience.scienceblog.com

Dr Sam Illingworth

We measure how much was let go,With gadgets on the ground below;

Blasé to what we might install,The rain it continues to fall.

Our noses can pick up its scent,

Whilst Radar can say where it went;And indifferent to it all,

The rain it continues to fall.

Computers predict the locale,Umbrellas resist its morale;

Nonchalant through drizzle and squall,The rain it continues to fall.

We dance for its blessing to come,We pray that we will not succumb;

Yet oblivious to our call,The rain it continues to fall.

Rainfall Radar

+Weather Facts

On January 22 1943, the temperature

at Spearfish, South Dakota rose

27°C in just 2 minutes

The warmest autumn on record for the UK was in

2006 with average temperatures of

11.4oC

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At any particular time, there are approximately

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occurring in the Earth’s atmosphere

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A rainbow was visible for

6 hours Wetherby, Yorkshire on 14 March 1994

Documents

theWeather Club Newsletter · the UK, ‘Wimbledon week’ saw a change to more warm and sunny conditions, with long, dry, settled spells and short interludes of exceptional warmth