F. tropical storms

Global atmospheric circulation

The large-scale movement of air around the Earth, driven by temperature and (air) pressure differences

Hadley Cells/ mid-latitude cells

• Equator is the most humid area as the sun’s rays are most concentrated

• Evaporation occurs because of the heat and the air rises

• As it rises it cools

• This condenses the initially vaporised moisture and causes rainfall

• As it depletes it turns into warm dry air

• It then has to get out of the way of the equator as the rest of the evaporated air rises

• It then sinks down where some of it drifts back to the equator and the cycle repeats as an atmospheric cell

Anticyclone

Air is sinking towards the ground/ surface from areas of high pressure e.g. North Pole

Cyclone

Air is rising from the ground/ surface from areas of low pressure on the ground e.g. at the equator

Coriolis effect

Results from differences in velocity as the earth spin

Tropical storm

A localised very intense low pressure wind system forming over tropical oceans with winds of hurricane force

Where are hurricanes found?

Near the connection between N. and S. America above equator

Where are cyclones found?

Above and below equator in the north of Australia and east of Africa and south of Asia

Where are typhoon found?

South-east of Asia above equator in pacific ocean

Where are westerlies found?

In the mid-latitude cells away from the equator

Where are southeasterly trades found?

South of the equator going to the equator

Where are northeasterly trades found?

North of the equator going to the equator

Why dont tropical storm occur at the equator?

Due to the Coriolis effect and the Hadley cells changing path away from the equator

What is the first step to form a tropical storm?

Strong upward movement of air draws vapour up from the warm ocean surface

What happens after ‘Strong upward movement of air draws vapour up from the warm ocean surface’?

Evaporated air cools as it rises and condenses to form towering thunderstorm clouds

What happens after ‘Evaporated air cools as it rises and condenses to form towering thunderstorm clouds’?

As the air condenses it releases heat which powers the storm and draws up more and more water from the ocean

What happens after ‘As the air condenses it releases heat which powers the storm and draws up more and more water from the ocean’?

Several smaller thunderstorms join together to form a giant spinning storm

What happens after ‘Several smaller thunderstorms join together to form a giant spinning storm’?

The storm now develops an eye at its centre where air descends rapidly

At what wind speed does it become a tropical storm?

120km per hour

What happens after ‘The storm now develops an eye at its centre where air descends rapidly’?

As the storm carries across the ocean by the prevailing winds, it continues to gather strength

Where are the most intense weather conditions felt?

The eye wall

What happens after ‘As the storm carries across the ocean by the prevailing winds, it continues to gather strength’

On reaching land the storm’s energy supply (evaporated air) is cut off. the friction  with the land slows it downvand it begins to weaken

What happens if the storm reaches warm sea again after crossing land?

It may pick up strength again

Features and structure of a tropical storm

How does climate change effect the frequency of tropical storms?

• Frequency may increase in future

How does climate change effect the intensity of tropical storms?

• Sea surface temperatures/ atmosphere temperatures increasing potentially causing more intense storms

• More data necessary before deriving conclusion

How does climate change effect the distribution of tropical storms?

• Surface temperatures increased by 0.25-0.5 degrees celsius

• With overall temperatures increasing it is possible for tropical storms to emerge out of previously cool waters