Why do we have weather?Why do we have weather?

1.1. The sunThe sun is what causes us to have weather. is what causes us to have weather. As solar energy reaches the Earth, the air As solar energy reaches the Earth, the air masses at the equator heat up more than at masses at the equator heat up more than at the poles. the poles.

2.2. Warm air and water at the equator travel Warm air and water at the equator travel toward the polestoward the poles

3.3. Cold air and water at the poles travel toward Cold air and water at the poles travel toward equator equator

4.4. It is the It is the atmosphere's struggle for atmosphere's struggle for temperature balance temperature balance that brings us our that brings us our changing weather. changing weather.

The Atmosphere’s StruggleThe Atmosphere’s Struggle

An air mass is a large dome of air which has similar

temperature and moisture characteristics.

What is a storm?What is a storm?

Storms are very Storms are very simple to understandsimple to understand

Areas in our Areas in our atmosphere that have atmosphere that have low air-pressure low air-pressure and and winds that spiral in winds that spiral in toward the toward the centercenter form form the many different the many different types of storms.types of storms.

Types of stormsTypes of stormsExtratropical storms: Extratropical storms:

Form outside the tropicsForm outside the tropics Center of storm is colder than Center of storm is colder than

the surrounding airthe surrounding air Has frontsHas fronts Strongest winds in the upper Strongest winds in the upper

atmosphereatmosphere Causes tornadoes, Causes tornadoes,

thunderstormsthunderstorms Tropical stormsTropical storms: : Form over a tropical oceanForm over a tropical oceanCenter of storm is warmer Center of storm is warmer than the surrounding air than the surrounding air Has no frontsHas no frontsStrongest winds are near Strongest winds are near the Earth's surfacethe Earth's surfaceCauses hurricanes, typhoonsCauses hurricanes, typhoons

What is a Front?What is a Front?When 2 air masses with different properties meet and When 2 air masses with different properties meet and do not combine together, the area between them is do not combine together, the area between them is called a front.called a front.There are 4 types of fronts:There are 4 types of fronts:

Cold Front Warm FrontCold Front Warm FrontOccluded Front Stationary FrontOccluded Front Stationary Front

What is a cold front?What is a cold front?

A Cold Front…A Cold Front… forms when warm air moves forms when warm air moves upup, and cold air rushes in , and cold air rushes in beneathbeneath it. it. the air masses crash together and the cold front goes the air masses crash together and the cold front goes downdown and the warm front goes and the warm front goes upup. .

A Warm Front forms…A Warm Front forms…

……when a when a mass of mass of warmwarm air overtakes a air overtakes a coldcold air mass air mass and moves and moves

over it. over it.

Steady rain and light showers usually are Steady rain and light showers usually are associated with Warm Fronts.associated with Warm Fronts.

What do they mean by Occluded?What do they mean by Occluded?To occlude means to block or hide someone or something.To occlude means to block or hide someone or something.

An Occluded Front…An Occluded Front…o forms when a forms when a Cold FrontCold Front overtakes a overtakes a Warm FrontWarm Front. . o produces less extreme weather such as rain and windproduces less extreme weather such as rain and wind

Since a cold front is the boundary between cool and warm air when the cool air is replacing the warm air, and a warm front is the boundary when the warm air is winning the battle in the sky…what happens when neither one is winning?

This known as a stationary front. Stationary fronts often bring several days of cloudy, wet weather that can last a week or more

The Tale of the Fighting FrontsThe Tale of the Fighting Fronts

A Tornado is…A Tornado is…1. A violent whirling wind, extending

from the base of a thunderstorm cloud to the ground.

2.2. A tornado over a lake or ocean is A tornado over a lake or ocean is called a waterspout.called a waterspout.

TornadoesTornadoesThe most destructive winds – speeds of The most destructive winds – speeds of up to 310 mph -- faster than Indy 500 up to 310 mph -- faster than Indy 500 race carsrace cars

Winds act like a vacuum -- sucks up air Winds act like a vacuum -- sucks up air that crashes together and spinsthat crashes together and spins

…..After

Before…

MicroburstsMicroburstsVery concentrated bursts of Very concentrated bursts of airair that that blastblast down from thunderstorms. down from thunderstorms.

In a Microburst, air falls In a Microburst, air falls at speeds of 90 mph (in at speeds of 90 mph (in normal storms air falls normal storms air falls

about 10 mph) about 10 mph)

The name "monsoon" comes from an Arabic word The name "monsoon" comes from an Arabic word which means which means "season" or "wind-shift". "season" or "wind-shift". Arizona MonsoonsArizona Monsoons occur during the late summer occur during the late summer months.months.In the winter, wind flows to Arizona from California In the winter, wind flows to Arizona from California and Nevada. and Nevada. In the summer, the winds shift bringing moisture In the summer, the winds shift bringing moisture from the Pacific Ocean and the Gulf of Mexico. from the Pacific Ocean and the Gulf of Mexico. This change, together with daytime heating, This change, together with daytime heating, brings Arizona monsoons. brings Arizona monsoons.

How a Monsoon formsHow a Monsoon forms

Are Monsoons only in Arizona?Are Monsoons only in Arizona?

No, the most well known No, the most well known monsoons are those monsoons are those which affect India and which affect India and Southeast Asia. Southeast Asia.

The summer monsoon The summer monsoon blows southwest across blows southwest across the Indian Ocean and is the Indian Ocean and is extremely wet. extremely wet.

The winter monsoon The winter monsoon blows northeasterly and blows northeasterly and is generally dry.is generally dry.

Dust DevilsDust DevilsLook like mini tornadoes, Look like mini tornadoes, but tornadoes form high but tornadoes form high in the sky, devils form on in the sky, devils form on the the groundgroundHappens when ground Happens when ground gets really gets really hot hot and heats and heats up up airair;air rises fast and ;air rises fast and bangs together, spinning bangs together, spinning aroundaroundSucks up dust and dirtSucks up dust and dirtFastest devils spin about Fastest devils spin about 40 mph40 mph

Hurricanes are actually a kind of Tropical StormsHurricanes are actually a kind of Tropical Storms

Tropical storms are large rotating storm systems that form in the Atlantic, Tropical storms are large rotating storm systems that form in the Atlantic, Indian, and Pacific oceans. Indian, and Pacific oceans.

In the Atlantic and eastern In the Atlantic and eastern Pacific they are called hurricanes. Pacific they are called hurricanes. In the western Pacific they are In the western Pacific they are known as typhoons, which means known as typhoons, which means “ “great winds” in Chinese. great winds” in Chinese. Those in the Indian Ocean are Those in the Indian Ocean are called cyclones, or by Australians, called cyclones, or by Australians, willy-willies. willy-willies. No matter which term is used, they No matter which term is used, they all describe this phenomenonall describe this phenomenon

How a hurricane beginsHow a hurricane begins

Great Hurricane of 1938Great Hurricane of 1938 The eye was about 50 miles across The eye was about 50 miles across and the hurricane was about 500 miles and the hurricane was about 500 miles wide. wide. Winds gusting over 180 mph and Winds gusting over 180 mph and waves between 30 and 50 feet pounded waves between 30 and 50 feet pounded the coastline with millions of tons of sea the coastline with millions of tons of sea water.water. Entire homes and families were swept Entire homes and families were swept into the sea. into the sea. Most people did not even realize that Most people did not even realize that a hurricane was upon them even as the a hurricane was upon them even as the waters began flooding their coastal waters began flooding their coastal homes. homes. Providence, Rhode Island was 20 feet Providence, Rhode Island was 20 feet underwater while Westhampton Beach, underwater while Westhampton Beach, a mile inland, was under 8 feet of water! a mile inland, was under 8 feet of water!

Types of PrecipitationTypes of Precipitation

Rain - Rain - Liquid drops of water which fall from the cloudsLiquid drops of water which fall from the clouds

Snow - Snow - Falling ice formed when water vapor turns into ice.Falling ice formed when water vapor turns into ice.

Sleet - Sleet - Drops of rain that freeze into ice as they fall.Drops of rain that freeze into ice as they fall.

Hail - Hail - Falling ice balls formed during thunderstorms. Falling ice balls formed during thunderstorms.

SnowstormsSnowstorms

Rainstorms and SnowstormsRainstorms and Snowstorms

Rainstorms and Snowstorms are produced Rainstorms and Snowstorms are produced when two different fronts collide. (A warm when two different fronts collide. (A warm hitting a cold or a cold hitting a warm.)hitting a cold or a cold hitting a warm.)

Major effects could be huge blizzards, ice Major effects could be huge blizzards, ice storms and heavy rainstorms also known storms and heavy rainstorms also known as Monsoons.as Monsoons.

BlizzardsBlizzards

In the winter, when a In the winter, when a warmwarm front moves front moves in and meets a in and meets a coldcold front, clouds front, clouds develop and heavy develop and heavy snowfall snowfall occurs.occurs.There are ice crystals in clouds. When There are ice crystals in clouds. When many tiny crystals build up, they fall to many tiny crystals build up, they fall to the Earth as snow.the Earth as snow.A blizzard is a name for a violent, A blizzard is a name for a violent, bitterly cold wind with blowing snow bitterly cold wind with blowing snow whipped up from the ground.whipped up from the ground.

What makes a snowstorm into a What makes a snowstorm into a blizzard?blizzard?

A snowstorm becomes a A snowstorm becomes a blizzard when you can’t blizzard when you can’t see very far ahead of you see very far ahead of you for three or more hours. for three or more hours.

Winds of 35 mph or more Winds of 35 mph or more along with lots of falling along with lots of falling and/or blowing snowand/or blowing snow

Temperature of less than Temperature of less than 20 degrees20 degrees

ThunderstormsThunderstorms

Thunderstorms are produced when Thunderstorms are produced when coldcold fronts move in and meet warm fronts. fronts move in and meet warm fronts.

Thunderstorms are heavy rainstorms Thunderstorms are heavy rainstorms accompanied by accompanied by thunderthunder and and lightning. lightning.

Thunder and LightningThunder and Lightning

Thunder is created when lightning heats up the air around Thunder is created when lightning heats up the air around it and causes it to expand rapidly. it and causes it to expand rapidly.

Since light travels very fast, you see lightning as it Since light travels very fast, you see lightning as it happens. happens.

Sound travels much slower than light and takes much Sound travels much slower than light and takes much longer to get to you. You hear the thunder longer to get to you. You hear the thunder afterafter you see the you see the lightning. lightning.

It takes thunder 5 seconds to travel one mile. After you see It takes thunder 5 seconds to travel one mile. After you see a flash of lightning, start counting seconds until you hear a flash of lightning, start counting seconds until you hear the thunder. Divide the number of seconds by 5. This is the the thunder. Divide the number of seconds by 5. This is the number of miles away the lightning is. number of miles away the lightning is.

Hailstorms and HailstonesHailstorms and Hailstones

Hail forms when strong Hail forms when strong currents of rising air carry currents of rising air carry rain from thunderstorms rain from thunderstorms upwards where it freezes upwards where it freezes into ice. into ice.

Hail often melts before it Hail often melts before it reaches the ground, but in reaches the ground, but in sometimes ice chunks the sometimes ice chunks the size of softballs pound the size of softballs pound the countrysidecountryside

FloodsFloods

A flood occurs when A flood occurs when a body of a body of waterwater rises and overflows rises and overflows onto normally onto normally drydry land. land.

Coastal FloodingCoastal Flooding

Caused by high, wind-Caused by high, wind-generated water waves, generated water waves, high tides, erosion of high tides, erosion of coastal areas, and coastal areas, and tsunamis (underwater tsunamis (underwater earthquakes). earthquakes).

Coastal flooding is a Coastal flooding is a big concern because, in big concern because, in many people live along many people live along coastlines all over the coastlines all over the world. world.

River FloodingRiver Flooding

When it rains and snow When it rains and snow melts, the soil can only melts, the soil can only absorb water a certain absorb water a certain amount of water in a amount of water in a short period of time. short period of time.

The longer it rains, the The longer it rains, the more likely it is that more likely it is that rainwater will build up rainwater will build up on the ground as runoff on the ground as runoff and overflow lakes, and overflow lakes, rivers and streams.rivers and streams.

Caused by extremely Caused by extremely intense intense rainfall, 10 inches rainfall, 10 inches or more an or more an hour,hour, for a for a short period of time.short period of time.

Common in mountainous Common in mountainous areas, where steep slopes areas, where steep slopes cause water to travel at cause water to travel at high speeds, causing high speeds, causing erosion. erosion.

These floods often occur These floods often occur with little warning.with little warning.

Flash FloodsFlash Floods

Is there anything Is there anything goodgood about a flood? about a flood?Floods cause disasters, Floods cause disasters, but they can also be but they can also be beneficial. When a river beneficial. When a river overflows, it dumps sand, overflows, it dumps sand, silt and debris that is silt and debris that is carried downstream onto carried downstream onto the surrounding land. the surrounding land.

After the flood waters After the flood waters move away, the soil is move away, the soil is more fertile, because of more fertile, because of the organic matter and the organic matter and minerals that were in the minerals that were in the water. water.