Atmosphere (Achieve ) Flashcards
Insolation
- what does insolation refer to / what is it?
-How is insolation measured?
-How much insolation reaches the earths surface?
-What is the albedo?
-The energy of the sun is the original source of most of the energy found on earth.
-The term insolation is derived from the words ‘incoming solar radiation’.
-Insolation refers to the amount of solar radiation that reaches the earth’s surface.
-Insolation is measured by the amount of solar energy received per square centimetre per minute.
-Some insolation reaches Earth’s surface without interference and some is absorbed by gas molecules and dust in the atmosphere.
-This means that only 52% of the insolation reaches the earth’s surface and 48% is reflected back to the space by the atmosphere.
-Albedo is the measure of how much light that hits a surface is reflected without being absorbed.
Tropical Latitudes
- curve of the earth
-Intensity of insolation
-Suns rays
Due to the curve of the Earth the sun’s rays are concentrated on a much smaller surface area over the tropical latitudes, resulting in more energy.
The intensity of insolation is greatest on the equator because the angle of the sun is higher, at close to 90o.
The Sun’s rays are more concentrated, as the midday Sun is high in the sky throughout the year.
Rays have less atmosphere to pass through at the Tropics so less energy is lost through absorption and reflection.
The darker forested areas and dense vegetation in the Tropics absorb radiation so albedo is lower.
Polar Latitudes
-Curve of the earth
-Sunlight
- tilt of earth
Due to the curve of the earth, the sun’s angle of insolation is lower at the poles so the rays of energy are spread out over a much larger area and are therefore less intense.
The sunlight travels at an angle and so through more distance of atmosphere, which means less energy reaches the surface of polar regions.
Lighter snow/ice covered areas at the poles reflect more radiation and so polar regions have a higher albedo.
Due to the tilt of the Earth there is no insolation at the poles during the winter solstices/tropical areas receive insolation all year round.
Circulation cell
- The equator
- Air converged where?
The equator receives more direct radiation from the Sun. A ray of light from the Sun hits the ground at an angle near the poles so it’s spread out more. More radiation at the equator means the ground (or ocean) is warmer, so it warms up the air, which rises.
When the air reaches the upper atmosphere at the equator it diverges, heading either north or south toward the poles.
From all around the hemisphere the air converges on the poles. The air is cooling as it moves away from the equator, and when it gets to the pole it sinks to ground level and then makes the journey back to the equator. It’s a cycle and known in Geography as a circulation cell.
Intertropical Convergence Zone (ITCZ)
- Where is Energy transferred from?
- Where does warm air rise?
- What does the air gradually do?
- Where does air move?
- What happens with the cold air from poles?
Energy is transferred from lower latitude energy surplus areas to higher latitude energy deficit areas by atmospheric circulation.
Warm air rises at the Equator to a height of 18 kilometres and travels in the upper atmosphere to around 30o N and S towards the poles, forming the westerlies.
The air gradually cools and sinks to the surface, flowing back to the equator.
Air moves from the tropical high to the low pressure area at the equator creating the Hadley Cell/Trade Winds.
Some of the rising air from the Equator travels in the upper atmosphere to the Poles where it sinks, forming the Polar cell.
Cold air sinking in the polar region moves to 60oN/S to form the Polar Cell/Polar Easterlies.
The cold air from the poles meets warmer air from the tropics, causing air to rise creating the Ferrel Cell.
The Ferrel Cells, which unlike the other cells, are not driven by temperature and they flow in the opposite direction to Hadley and Polar cells.
Overall, warm air from the Equator is distributed to higher and cooler latitudes and cold air from the Poles distributed to lower and warmer latitudes.
If there was no atmospheric circulation, lower latitudes would get hotter and hotter and higher latitudes colder and colder.