Weather hazards Flashcards
(37 cards)
Where are tropical storms found?
Either side of the equator, between 5° and 20° north and south
NOT ON THE EQUATOR
Define a tropical storm
Tropical storms are intense low pressure systems formed over tropical waters.
When are tropical storms most common?
Mid-august to october
What weather conditions do tropical storms bring?
Really strong winds and torrential rain.
How fast does the wind have to be to be classified as a hurricane?
74mph
What does the Saffir-Simpson scale measure?
Why isn’t this always that helpful in measuring potential damage?
It measures wind speed and potential damage.
1-5 scale.
Not always helpful because if the place is near the sea there may be storm surges, the Simpson scale can’t measure a storm surge which creates the damage.
What happens when a hurricane hits land?
Looses all of its energy as it gains its energy from the warm water in the sea.
Can we predict storms?
No, but we can predict its path.
What 3 things does a tropical storm need?
- Low pressure
- Warm water 27°C +
- Coriolis effect
Which way does the wind bend in the Northern Hemisphere?
Wind bends to the right.
Which way does the wind bend in the Southern Hemisphere?
Wind bends to the left.
What happens to warm air?
It rises.
What happens to cold air?
It sinks.
What happens to the temperature of warm air when it rises?
It cools by 1°C every 100m.
What processes happen to the warm air when it rises?
It cools, condenses, forms clouds and rains.
When air rises what happens to the air pressure?
It decreases.
When air sinks what happens to the air pressure?
It increases.
Can it rain when there is high pressure?
No.
Surface winds blow from…?
High to low pressure.
What are high altitude winds called?
Jet streams.
What happens when air sinks?
Nothing, there will be no clouds, it will be dry.
Describe the Coriolis effect.
Winds blow from areas of high pressure to areas of low pressure.
As the earth rotates, it causes the winds to bend.
This is known as the Coriolis effect.
Describe the 6 stages of a hurricane forming.
- Hurricanes draw their energy from warm seas and can only occur over very warm water, 27° or more.
- Because the surface water is very warm it evaporates, rises and condenses into storm clouds.
- The rising air creates low pressure which pulls surface winds in from the edges of the storm.
- Where “vertical wind shear” is low, the clouds are prevented from breaking up as they rise. (vertical wind shear is the change in direction and speed of winds at increasing heights in the atmosphere)
- The storm spins because of the Coriolis effect.
- As the storm moves over the ocean the energy from the warm water strengthens the storm so the wind speeds increase.
Why does a tropical storm die out?
There are 2 reasons.
- When they hit cold water they lose their energy source (from the warm ocean water) and so begin to die out.
- As they pass over land friction slows them down.
