Atmosphere Flashcards
What is the Global Heat Budget?
The energy that the earth receives from the sun and how it is distributed
Describe the Earth’s heat budget
100% of the Earth’s energy comes from the sun
26% is reflected back into space by the atmosphere (clouds and dust particles)
18% is absorbed by the atmosphere (clouds)
56% reaches the Earth’s surface
50% is absorbed by dark coloured surfaces like vegetation
6% is reflected back by reflection from light coloured surfaces like snow and ice.
What is earth’s albedo?
Albedo is reflection of energy from white or light coloured surfaces like snow and ice.
Describe and explain the transfer of energy in a Hadley Cell
Sun’s energy heats the earth at the equator and this heats the air above it making it less dense.
The warm air rises, creating an area of low pressure.
As the air rises it cools, becomes more dense and sinks back to earth.
The sinking air creates an area of high pressure at 30 degrees north and south of the equator.
The air then moves back towards the area of low pressure at the equator known as the north east trade winds in the northern hemiphere.
This circulation of air is known as a Hadley Cell.
Describe and explain the transfer of energy in a Polar Cell
Cold, dense air sinks ove rthe pole at 90 degrees north (and south).
The air moves towards 60 degrees north and is warmed.
This movement creates the polar easterlies winds.
As the warmer air reaches 60 degrees north it begins to rise and forms an area of low pressure.
The air cools as it rises and moves north to complete the circulation of the Polar Cell.
What is a Ferrel Cell?
A Ferrel cell is not a true cell of atmospheric circulation.
It forms due to the temperature differences between the Hadley and Polar cells.
It sits between the Hadley cell AT 30 degrees north and the Polar cell at 60 degrees north.
Dense air sinks at 30 degrees north and moves northwards by friction.
This creates the Westerlies winds.
Westerly winds bring warm air to places in 60 degree latitudes.
The air rises at 60 degrees north in the area of low pressure.
What is a Jet stream
A jet stream is a band of very fast moving air at 10,000-12,000m up in the atmosphere.
Jet streams occur due to differences in temperature between the different atmospheric cells.
Jet streams contribute to the movement of atmospheric energy around the planet.
What is a trade wind
Trade winds are found between 30 degrees north and south and the equator.
Trade winds are caused by the movement of air from teh high pressure subtropical zones at 30 degrees towards the low pressure zone at 0 degrees 9the equator)
What are the Westerly Winds
The westerly winds flow pole-wards from tjhe area of subtropical high pressure at 30 degrees towards the middle latitudes at 60 degrees
What is a gyre
A gyre is the circulation of water in the ocean.
A gyre brings warm water, which has been heated by intense sun’s energy at the equator. This warm water flows towards the northern latitudes (in the northern hemisphere).
Cold, polar water flows towards the equator creating a circulatory system or gyre.
What influences the circulation of gyres
Earth’s rotation creates coriolis effect deflects the flow to the right which makes the currents flow in a clockwise direction in the northern hemisphere. The opposite occurs in the southern hemisphere.
Land masses like NE Brazil ‘deflect’ the flow of currents.
Winds blowing over the currents assist the flow of water in the gyres.
Differences in density (warm water is less dense than cooler water) allow the currents to flow at different depths within the ocean and to transfer energy.
What does ITCZ stand for
Inter Tropical Convergence Zone
What happens in a zone of convergence
A zone of convergence is where winds meet.
Converging winds include trade winds, which meet at the Equator in a zone known as the ITCZ
Briefly explain the seasonal movement of the ITCZ
The zone of convergence moves northwards and southwards with changes in the sun’s seasonal movement between the tropics of cancer and capricorn.
The movement of the ITCZ affects the climates of areas like west Africa, especially rainfall patterns.
As the ITCZ shifts its position throughout the year, it brings wet and dry seasons to the area.
Describe the characteristics of the 2 air masses which meet at the ITCZ
The Tropical Continental air mass originates over the Sahara Desert.
Its characteristics are warm and dry conditions.
The Tropical Maritime air mass originates over the Bay of Guinea in the Atlantic Ocean.
Its characteristics are warm and wet conditions.
