Weather Notes Unit 1 – Part 2

Weather, Climate Change and

Society

Part 2 – Chapter 2

Textbook P. 43-89

Measuring Weather Data

Weather forecasting – involves predicting what the future weather will be

based on ongoing observations of atmospheric conditions.

Involves qualitative data – observations that involve senses

Involves quanitative data – observations based on measured data

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4

1)Anemometer – is a device used to

measure wind speed

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6

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8

High air pressure in a region indicates fair weather while low pressure indicates that storms are more likely.

Normal barometer

reading 103.1 kPa

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5.

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6. Weather satellite – space craft that orbits the earth collecting weather

related data to send messages to weather stations on earth

7. Weather Balloons – helium filled balloons that have weather

equipment attached – released into the atmosphere to collect weather

related data.

8. Computers – data collected are analyzed and presents as weather

forecasts

9. Radar – useful to track and detect severe weather (thunderstorms,

hurricane, etc.

13

Humidity Humidity:

a measure of the amount of water vapor in the air

Warm air can hold more moisture then cold air

Relative Humidity:

The measure of the amount of water vapor compared to the Maximum amount possible

Other important weather related terms!!

Saturated Air

Relative humidity is 100%

Over 100% results in condensation

Dew Point

Temp at which dew forms

As air gets colder, it holds less moisture

Releases excess as dew

Large amounts of energy is needed to

overcome the forces of attraction

between water molecules in the

atmosphere in order for water to

evaporate, while large amounts of

energy is released when water

molecules condense!!

Effects of Humidity

Higher humidity

causes perspiration to evaporate slowly.

Sweating doesn’t cool us as well

Low humidity

Air is dryer

Skin may be

uncomfortable

Humidex:

Reports how hot the

humidity makes us feel

Analyzing a weather Report – P. 49 text

Describe daily weather

Be sure to include….. 1. Sky cover – clear, a few clouds, scattered clouds,

partly cloudy, mostly cloudy, overcast

2. Precipitation intensity – light moderate, heavy

3. precipitation measure – mm or cm – rain gauge

4. relative humidity - % - hygrometer ir sling psycrometer

Temperature – Celsius – thermometer

Wind direction – wind vane and compass points

Include definite digits and one estimated digit

Forecasting the Weather

Short Range Forecast

A forecast that predicts how

weather conditions will change

over a 48 hour period

Usually more accurate

Look at location of weather fronts,

speed and directions

Look at pressure systems and

boundaries

Isotherms/isobars

Long Range Forecast

A weather forecast that predicts

how the weather will change over

a period of 3 to 7 days

Not as accurate – why??? P. 56

More computer bases statistical

analysis – computer models of

atmospheric circulation and

behaviours

Weather forecasts will vary to a certain degree of uncertainty!

Varies with how far it is predicted in the future

The atmosphere is unreliable and can change quickly

P. 10

What is an isotherm?

Isotherms are lines of constant or equal temperature.

They are often used on weather maps by meteorologists

to give a large scale view of temperatures across the U.S.

If you have ever looked at a weather map in a newspaper,

the isotherms are used to divide the color-filled

temperatures.

What is an isobar?

Isobars are lines of constant or equal pressure on a

weather map. They can be used to find areas of low or

high pressure over a broad area (like the U.S.), and they

can tell us how intense the system may be. On weather

maps, you may have noticed areas that have a large “L”

or “H” over a region with lines circling around them. The

“L” stands for low pressure (where we would expect to find

the lowest pressure) and “H” stands for high pressure

(where we would expect to find the highest pressure). The

lines circling them are isobars. Generally the lowest

pressure is where precipitation is most likely to fall, and

high pressures are usually associated with clear and

sunny conditions. Where the isobars are close together,

windy conditions may be expected. Elongated areas of

low pressure on surface and upper air weather maps are

called "troughs" and elongated areas of high pressure are

called "ridges."

Closer together, stronger wind and low

pressure system

https://www.theweathernetwork.com/ca/hourly-weather-

forecast/newfoundland-and-labrador/wabush

The weather network

The dew point is the temperature the air needs to be

cooled to (at constant pressure) in order to achieve

a relative humidity (RH) of 100%. At this point the air

cannot hold anymore water in the gas form. If the air

were to be cooled even more, water vapor would

have to come out of the atmosphere in the liquid

form, usually as fog or precipitation.

The higher the dew point rises, the greater the

amount of moisture in the air. This directly effects how

"comfortable" it will feel outside.

General comfort levels that can be expected during

the summer months:

less than or equal to 55: dry and comfortable

between 55 and 65: becoming "sticky" with muggy

evenings

greater than or equal to 65: lots of moisture in the air,

becoming oppressive

https://eldoradoweather.com/canada/weatherglance.html

The weather office

https://eldoradoweather.com/satellite

/ssec/conus-us-composite/conus-

color-composite.php

Active satellite map

Canadian Contributions to weather related technology

1. 3 cup anemometer

2. humidex scale

3. UV index

4. LIDAR – Mars Phoenix spacecraft P. 50 in textbook

5. Andre Robert – first computer bases simulations of weather patterns and forecasts

6. Canadian GEM forecasting global model

Weather-related knowledge is not static – it changes with increased knowledge

and technological advances

Climate Change – P. 68

Greenhouse gases—water vapor, carbon, methane, and

nitrous oxide—trap heat in our atmosphere. Those gases are

neither “good” nor “bad.” They are natural.

For more than a century, humans have been sending extra

greenhouse gases into our atmosphere, from industrial and

agricultural activities. We are tampering with the balance of

gases in our atmosphere. It is now trapping too much of the

sun’s heat, so that our planet cannot properly cool off. We’re

throwing the regulation mechanisms out of whack.

This has created global warming. Our average temperatures

are climbing steadily, and dangerously. This is such an

enormous change that it is almost impossible to believe. But

there is no disagreement among serious climate scientists. We

are changing our climate. And we are beginning to see,

feel—and suffer from—the results.

Review Questions – P. 77-70