atmosphere Flashcards
explain why the earths surface only absorbs 50% of the energy received from the sun (8)
Scattering - 54%.
This energy is sent back into the atmosphere as long wave (infrared) radiation.
About 17% - reflected by clouds
8% - scattered by gas and dust particles,
6% - reflected from the earths surface, albedo affect
Absorption by the atmosphere - 23%
This is because 19% is absorbed by dust and gases, whilst 4% is absorbed by clouds
Explain why there is a surplus of energy at the equator and a deficit at the poles. You may use a diagram to support your answer. (8 marks)
surplus of solar energy in the tropical latitudes -the suns rays are more concentrated
The suns rays strike these areas at right angles - energy is less likely to be lost
Suns angle in the sky decreases towards the poles due to the curvature of the earth, - spreads heat energy over a larger surface area
Therefore, the suns rays have less atmosphere to pass through at the tropics, - less energy is lost through absorption and reflection by clouds, gas and dust
Tilt of the axis - sun being higher in the sky between the tropics throughout the year, focusing energy
No solar insolation at the poles for 6 months of the year, producing 24 hour darkness so the tropics receive much more insolation throughout the year
Th albedo effect - More radiation is absorbed at the tropics due to the vast amount of dark forestry eg the amazon rainforest
Explain the transfer of energy between the equator and the poles (10 marks)
the Hadley cell, direct heating of air at the equator, warm air rises which creates low pressure, air eventually cools and sinks over the tropics, making these high pressure zones,
Wind blows from high to low pressure, so some air is then returned to the equator as the trade winds
polar cell, At the poles cold air sinks, creating high pressure areas, air moves across the earths surface as the polar easterlies winds and it is warmed, rises at the subtropics and is then returned to the poles
The Ferrel cell sits between the other two cells, driven by friction from the moving air of the other cells, it takes in the warm air from the tropics and transfers it to the higher latitudes, reducing deficit at the poles and surplus at the tropics
trade winds transferring energy from the tropics to the equator and the westerlies transferring energy polewards from the tropics.
Coriolis effect - winds are deflected in the northern hemisphere they are deflected right, in the southern hemisphere they are deflected left
Describe the pattern of ocean currents and explain how these maintain the global energy balance (10 marks)
gyres - currents are set up in clockwise loops
Warm water from equatorial regions moves northwards across Atlantic - which brings warm tropical waters to the west of Scotland
Colder waters are transferred southwards towards tropical latitudes e.g. in the canaries current
Currents are driven by surface winds which create a frictional drag on the water surface
prevailing winds determine current direction
The Coriolis force deflects currents clockwise in the north Atlantic
Uneven heating and differences in salt content creates differences in water density, resulting in the ocean convection currents with warm less dense water moving across the ocean surface and cold dense water moving across the ocean floor
Land masses obstruct and divert the currents causing gyres between the major land masses
Discuss the origin, nature and characteristics of the maritime tropical and continental tropical air masses (6 marks)
The tropical maritime origin is the Atlantic Ocean
This air mass brings hot, unstable air causing rainfall and thunderstorms
Weather patterns vary
The continental tropical origin is the Sahara Desert.
This air mass brings very hot, dry, and stable air with low humidity
Weather conditions unchanging
