Weather Weather

Extreme WeatherExtreme Weather

SummarySummary

ThunderstormsThunderstorms TornadoesTornadoes FloodsFloods DroughtsDroughts Hurricanes, Typhoons & Tropical Hurricanes, Typhoons & Tropical

CyclonesCyclones BlizzardsBlizzards

ThunderstormsThunderstorms

Has lightning, thunder, heavy rain and Has lightning, thunder, heavy rain and sometimes hailsometimes hail

Need two conditions:Need two conditions: Moisture to form clouds and precipitationMoisture to form clouds and precipitation Strong lifting of air to make clouds that reach Strong lifting of air to make clouds that reach

high in the atmosphere. high in the atmosphere.

Thunderstorms Cont’dThunderstorms Cont’d Low temperature at high altitude creates Low temperature at high altitude creates

a large temperature difference with the a large temperature difference with the warm air that is lower.warm air that is lower.

The warm air rises quickly because of The warm air rises quickly because of this temperature difference.this temperature difference.

Water vapour rises and hits the cold air Water vapour rises and hits the cold air where it condenses making clouds.where it condenses making clouds.

Once the clouds are heavy enough rain Once the clouds are heavy enough rain falls in the downdrafts.falls in the downdrafts.

Thunderstorms cont’dThunderstorms cont’d

Thunderstorm clouds can reach higher Thunderstorm clouds can reach higher than airplanes travel so pilots must than airplanes travel so pilots must maneuver around them.maneuver around them.

As the thunderstorm reaches its end the As the thunderstorm reaches its end the flow of air becomes mostly downward.flow of air becomes mostly downward.

TornadoesTornadoes

Because of their extremely high winds Because of their extremely high winds tornadoes can cause more damage in a tornadoes can cause more damage in a short time than any other storm on Earth.short time than any other storm on Earth.

Tornadoes are a severe component of a Tornadoes are a severe component of a thunderstorm.thunderstorm.

It is very difficult to predict their path or It is very difficult to predict their path or even exactly where they are going to even exactly where they are going to occur.occur.

Tornadoes cont’dTornadoes cont’d

Fast rising air in a thunderstorm Fast rising air in a thunderstorm sometimes begins to spin forming a sometimes begins to spin forming a funnel of air and moisture.funnel of air and moisture.

Rising air is replaced by cooler air which Rising air is replaced by cooler air which increases rotation.increases rotation.

The The funnel cloudfunnel cloud produces a pressure produces a pressure difference that can pick objects up.difference that can pick objects up.

Wind speed can be as high as 500 km/h.Wind speed can be as high as 500 km/h.

FloodsFloods

Excess of water when the land can’t soak Excess of water when the land can’t soak up any more water.up any more water.

Can’t happen in Antarctica. Why not?Can’t happen in Antarctica. Why not? Two types of floods:Two types of floods:

FlashFlash BroadsideBroadside

Flash FloodsFlash Floods

Little or no warning.Little or no warning. Can happen in cities if the water can’t Can happen in cities if the water can’t

drain fast enough.drain fast enough. Happens more when mountain valleys or Happens more when mountain valleys or

gorges can’t accommodate spring rain gorges can’t accommodate spring rain and melting snow.and melting snow.

Can also occur when a dam bursts or Can also occur when a dam bursts or overflowsoverflows

Broadside FloodsBroadside Floods

Can cover large areas of land for months.Can cover large areas of land for months. Can be predicted days or weeks before.Can be predicted days or weeks before. Causes:Causes:

Rivers flood from mountain snow melting.Rivers flood from mountain snow melting. Winter of heavy snowfall followed by rainy Winter of heavy snowfall followed by rainy

spring.spring. More rain than normal so soil becomes More rain than normal so soil becomes

saturated.saturated. Tropical storms bring lots of rain.Tropical storms bring lots of rain.

DroughtsDroughts

No precipitation for a long time.No precipitation for a long time. Can cause wildfires.Can cause wildfires. Can last for long periods of time.Can last for long periods of time. Sometimes places flood from lots of rain Sometimes places flood from lots of rain

at one time and then have a drought at one time and then have a drought later.later.

Hurricanes, Typhoons Hurricanes, Typhoons and Tropical Cyclonesand Tropical Cyclones Same type of storm just located in different Same type of storm just located in different

places of the world.places of the world. Has to be near the equator where the water Has to be near the equator where the water

surface temperature is high enough (about 27surface temperature is high enough (about 27ºC)ºC) Happen when cyclones become large enough.Happen when cyclones become large enough. If wind speed is 63km/h its called a tropical If wind speed is 63km/h its called a tropical

storm; if wind speed is 119km/h its called a storm; if wind speed is 119km/h its called a hurricane.hurricane.

Typhoons and tropical cyclones can be worse Typhoons and tropical cyclones can be worse than hurricanes.than hurricanes.

HurricaneHurricane: western Atlantic Ocean, : western Atlantic Ocean, Caribbean Sea, Gulf of Mexico or eastern Caribbean Sea, Gulf of Mexico or eastern Pacific OceanPacific Ocean

TyphoonTyphoon: northwestern Pacific Ocean or : northwestern Pacific Ocean or China SeaChina Sea

Tropical CycloneTropical Cyclone: Australia area or Indian : Australia area or Indian OceanOcean

Hurricane DevelopmentHurricane Development Warm air above warm water rises quickly Warm air above warm water rises quickly

carrying moisture with it.carrying moisture with it. As this air reaches higher altitude the As this air reaches higher altitude the

water vapour condenses releasing heat water vapour condenses releasing heat and increasing speed of rising air.and increasing speed of rising air.

Rising air creates a low pressure area Rising air creates a low pressure area that cool dry air moves into.that cool dry air moves into.

Cool air at the top also swirls outward Cool air at the top also swirls outward and back down to be warmed again.and back down to be warmed again.

Hurricanes cont’dHurricanes cont’d

The core of the hurricane is called the The core of the hurricane is called the eyeeye..

The eye is the low pressure area that is The eye is the low pressure area that is calm with clear skies.calm with clear skies.

Hurricanes can carry lots of rainfall inland Hurricanes can carry lots of rainfall inland creating floods and destruction.creating floods and destruction.

BlizzardsBlizzards

Severe snow storm with strong winds Severe snow storm with strong winds and low temperatures.and low temperatures.

Winds must exceed 55km/h and visibility Winds must exceed 55km/h and visibility must be less than 0.5km.must be less than 0.5km.

Blizzards develop similarly to Blizzards develop similarly to thunderstorms but with snow because of thunderstorms but with snow because of the cold temperatures.the cold temperatures.

What are some dangers of blizzards?What are some dangers of blizzards?