Paper 1 - Atmospheric Circulation,Hurricanes Flashcards
(36 cards)
What happens to the sun’s rays at the North Pole?
The sun’s rays are deflected over a large area due to the curve of the Earth so there is less heating. Temperature is lower here.
What happens over the Equator?
The Sun’s rays are concentrated over a small area heating it strongly.
Wind moves from….
High pressure to Low pressure.
When the ground is heated by the Sun’s rays, the air is also heated. The warm always…
Rises. This warm rising air is called low pressure.
Where air cools in the upper atmosphere, it…
Sinks. Sinking air is called high pressure.
For every 100m gone up…
You lose 0.65’C
The air at the Equator is heated. This air then rises when it reaches the tropopause and then splits and moves towards the Poles….
Until it reaches 30’N and 30’S (Tropics of Cancer and Capricorn) where it sinks as the air cools creating High Pressure Zones. The air then returns to low pressure areas. These spinning circles of air are called Hadley Cells.
What happens near the Equator?
The air is rising by so for every 100m it rises, the surrounding air temp cools by 0.65 ‘C, dew point is reached and vapour condensed into droplets and a band of cumulonimbus clouds occur and rain occurs.
When the air sinks at 30’N and S, what do you get bands of?
High pressure with sinking air which creates areas of clear skies and the sinking air warms.
What is the Coriolis force?
The spin of the Earth causing 2 types of winds: NE and SE trade winds and the westerlies.
What are the Westerlies?
Prevailing winds from the west to east between latitudes between 30’ and 60’ latitude.
What are polar cells?
Cold sinks creating an area of high pressure and it flows towards the low pressure areas placated at the mid latitudes around Europe.
On its journey…..
It bumps into the warmer air heading to the poles. This forces air to rise causing low pressure 60’N and S.
What are hurricanes called in certain parts of the world?
US/ Caribbean - hurricanes
South Asia (India, Bangladesh) - cyclones
East Asia ( Philippines) - Typhoons
Australia - Willy-nilly’s
Describe the distribution of tropical revolving storms.(3m)
Tropical storms are 5’ and 30’ North and South of the Equator. Hurricanes affect the Caribbean and the USA from August - October and comes from the Atlantic Ocean. Typhoons affect East Asia e.g. the islands of Philippines from the western Pacific Ocean from May - December. Cyclones come from the Indian Ocean during the months October - November and affect South Asia e.g. India
Explain the two relationships between tropical storms and general atmospheric circulation. (3m)
Tropical storms occur in the tropics( mainly where the inter-tropical convergence lies(ITCZ)) and the surface winds are coming together at the Hadley Cell. Here, the sun’s rays are concentrated over a smaller area giving higher temperatures and raises sea temperatures to above 27’ degrees. This causes the warm, moist air to rise rapidly which means that condensation occurs which then releases latent heat that the powers the tropical storm. The veer from Coriolis force has to be light so it doesn’t rip the storm apart.
How does a tropical storm form?
Steps 1&2
- Air is heated above the surface of warm tropical oceans that are over 27’C. The warm air rises rapidly over warm air conditions
- The rising air draws up more air and large volumes of air from the Ocean causing strong winds.
Steps 3,4
- The Coriolis effect( trade winds blowing in opposite directions) causes the air to spin upwards around a calm central eye of the storm.
- As the air rises, it cools and condenses to form large, towering cumulonimbus clouds which generate torrential rainfall. The heat given off when the air cools powers the tropical storm.
Steps 5,6,7
- Cold air sinks in the eye therefore there’s no cloud so it’s drier and much calmer.
- The tropical storm travels across the ocean in the prevailing winds.
- When the tropical storm meets land, it’s no longer fuelled by the source of moisture and heat from the ocean so it loses power and weaken.
How does the Coriolis Force affect TRD?
The Coriolis force bends and spins the rising warm air. The spinning can be seen in satellite images. Hurricanes in the northern hemisphere bend to the right.
What direction do tropical storms travel in?
Sea: Ts travel from east to west due to the direction in which the Earth spins. When they hit land, they lose their energy source from the sea that powered them.
Land: as they pas over land, friction slows them down. As they lose energy, they change direction.
How will the distribution of TRS change due to climate change?
The regions where TS are experienced aren’t expected to change significantly as a result of climate change but with sea temps exceeding over 27’ in areas further north hurricanes will expand a little bit. E.g. 31’ N
How will the frequency of TRS change due to climate change?
There’s isn’t expected to be an increase however the number of category 4&5 hurricanes will increase while the number of 1,2&3 are expected to decrease.
How will the intensity of TRS change due to climate change?
There’s evidence of a link between warmer oceans and the intensity(destructive power) of tropical storms. They’re expected to become more intense by 2-11% by 2100. The number of severe category 4 or 5 storms have increased since the 1970’s.