Atmosphere

Question 1

1. Explain why only 50% of solar energy reaching the edge of the atmosphere reach the surface of the earth

Answer 1

Reflection

1. 25%. ~Clouds(17%) wvgd(8%)
2. Weather conditions - gases and dust
3. 6% surface albedo - polar ice caps and oceans

Absorption

4. 23%. ~clouds(4%) wvgd(19%) - store
5. 46% absorbed by earths surface
   
   • dark coloured rainforest - absorbs energy

Question 2

2. Explain why there is a surplus of energy in the tropical latitudes and a deficit of solar energy towards the poles

Answer 2

Tropics - surplus - polar regions - deficit
•sphere - concentrated (vertical rays) - (further away from tropics)less intense - larger S.A
•(tropics) perpendicular angle - reflection
•(polar) angle - reflected
•(tropics)less atmosphere - less reflected
(Poles) more atmosphere - more reflection
•surfaces that absorb - rainforest
Light coloured surfaces - reflect - ice caps
•tilt of earth - directly overhead all year(at equator) - many months of darkness( poles)

Question 3

3. Explain how circulation cells in the atmosphere and the associated surface winds assist in the transfer of energy between areas of surplus and deficit

Answer 3

~Hadley~
Intense heat - low pressure - rises - cools - falls - replaces rising hot air - subtropical high to equatorial low ~~~north east trade winds

~Polar~
Subside - high pressure - cold condensed air meets warm subtropical air - rises ~~~polar easterlies

~Ferrel~
Response to two thermally opposite cells - feeds warm air to poles and cold air to tropics - pressure gradient - subtropical high at 30N to low at edge of polar cell (60N) ~~~mid-latitude westerlies

Coriolis force
Produced by earths rotation - right angles to rotation of earth - deflecting winds to right in northern hemisphere and left in Southern Hemisphere

Pressure and wind
High to low ~ pressure gradient force
Jet streams - temperature difference - polar and subtropical

Question 4

4+5. Explain how ocean currents help maintain global energy balance

Answer 4

Atmosphere and ocean circulation are closely connected - heat machine - 70% water - 70% global insolation - 20% redistribution of energy

Energy balance - equator-> poles=warm currents(North Atlantic drift) - poles->equator=cold currents(labrador current)

Clockwise~northern hemisphere - anti-clockwise~southern hemisphere - clockwise loop formed with warm water~ Gulf Stream~northwards - cooler~southwards~canaries current

Prevailing winds - friction
Coriolis force - 45* to the right of prevailing winds
Three closed loops=GYRES -major land masses - deflect

Dense and sink - warm currents to rise - conveyor belt

Question 5

6+7. Explain the variation in rainfall within west Africa

Answer 5

ITCZ - low pressure area, air rises cools and condenses
~300-500km south - local variation
Highest total rainfall - Tropical maritime air mass - most of the year
Twin peak - ITCZ tracks north in summer - south in winter
Peak rainfall - 2 months after áreas at coast - Takes time - associated conventional rainfall - tropical maritime air mass
Very little rainfall - fails to reach or only reaches for very short period
Sahara desert - fails to collect any moisture