Geography - Global Hazards
- Created by: Issy.ryan
- Created on: 28-12-17 09:59
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- Geography - T1- Global Hazards, Atmospheric Circulation
- Ferrel Cell
- Next to Hadley Cell, between 30° N/S and 60° N/S.
- Opposite direction to other cells, air joins the sinking air from the Hadley Cell and is moved from the high to low pressure belts, at 60° N/S, at low heights.
- The high pressure belt at 30° N/S has cloudless skies and low rainfall, often very hot.
- At 60° N/S, the air rises and meets with the polar air and the warm air rises. This is a low pressure belt, with frequent rain.
- Winds are large scale movements of air from high to low pressure.
- Winds are part of global atmospheric circulation loops, called cells.
- When warm air rises it creates low pressure belts, when cool air falls it creates high pressure belts.
- There are three main loops in each hemisphere, Hadley, Ferrel and Polar
- Usually 10 -15km high
- Warm air rises as less dense than cool air, it cools and condenses, forming clouds and rain.
- Cool air sinks as it is denser, meaning no clouds formed and is sunny.
- Polar Cell
- Furthest away from equator, from 60° N/S up or down.
- Some of the warm air rising from the Ferrel Cell moves towards the poles.
- The air is cooled and sinks at the poles, creating high pressure, with low temperatures.
- The high pressure air moves back towards the equator.
- Climate Zones
- Polar = low temperatures all year
- Temperate = moderate summers and winters, rainfall is frequent due to rising air from Ferrel Cell.
- Arid (dry) = rainfall is very low due to high pressure in-between Ferrel and Hadley Cell. Temperaturea very hot in the year.
- Tropical = temperatures are hot all the time, and rainfall is high due to the low pressure belt at the equator. Very humid conditions.
- Extreme Weather
- Wind
- Wind is air moving from areas of high to low pressure, meaning some areas are windier than others.
- Winds are weak in high and low pressure belts and strong in-between.
- When the difference is large between the high and low pressure areas, the winds can be extremely strong.
- Temperature
- The equator receives the most energy from the sun, the poles receive the least.
- Temperatures can be very high at high pressure areas like at 30° N/S because the sinking air creates no clouds, so there is nothing to absorb and block the sun's energy.
- However, at the high pressure belts of the poles, the temperatures are very low because the sun's rays barely heat them.
- Precipitation
- Precipitation (rain, snow etc) ocurrs when warm, wet air rises, cools and condenses.
- Air rises at the low pressure belts, meaning there is higher rainfall in these areas. E.g rainforests have high rainfall as they are in low pressure belts.
- The exact location of the high and low pressure belts changes over time, so countries between them can also have varied weather over time.
- Wind
- Ferrel Cell
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