2.2. The Global Energy Budget Flashcards
Troposphere
The first major layer of Earth’s atmosphere. It is warmer when nearer to Earth but then gets colder towards the Stratosphere. It is 8-20km high.
Stratosphere
The second major layer of Earth’s atmosphere. It is colder at the lower stratosphere, where it is near the Troposphere, but is warmer at high stratosphere.
Solstice
Two times of the year when the sun reaches its highest point in the sky at noon, marked by the longest and shortest days. There are 2 solstices: Winter and Summer.
Equinoxes
Two times of the year where the sun crosses the celestial equator, when day and height are of equal length. This is when the sun shines perpendicular to the equator.
Why is there more long-wave radiation in the North than South?
The South has Antartica, so more there is more albedo from the ice sheets and more radiation is reflected
Why are there 2 peaks for long wave radiation?
There are desserts at the tropics of Cancer and Capricorn, so there are no clouds and longs of long wave radiation can escape
Why is there a dip at around the equator for long wave radiation?
There are lots of rain forests at the equator, so more cloud cover and long wave radiation cannot be emitted and escape.
Radiation Balance of the Earth
- Latitude along x-axis - 90 North to 90 South
- Two y-axis, measuring radiation balance in watts / meters squared
- Short-wave solar radiation graph at equator shaped like a mountain - more radiation near equator
- Long-wave Earth radiation higher at the poles, lower near the equator. it has 2 peaks and a dip at equator.
- At equator there is a surplus of radiation
- At poles there are deficits
Inter-tropical Convergence Zone
A band few kilometres wide in which winds from the tropics blow inwards, converge and then rise, forming an area of low-pressure
Air Pressure
Weight of atmosphere gas pressing down on the Earth’s surface
Cold air has high or low pressure
High Pressure
Warm air has high or low pressure
Low Pressure
Isobar
Lines that show pressure
Summer Solstice
The Earth is tilted right. At the summer solstice, the sun shines from the right and shines perpendicular to the tropic of Cancer, so the tropic of Cancer gets the most sunlight. This is during June.
Winter Solstice
The Earth is tilted right. At the Winter solstice, the sun shines from the left and shines perpendicular to the tropic of Capricorn, so the tropic of Capricorn gets the most sunlight. This is during December..
ITCZ movement
- The ITCZ migrates North in July and South in January due to the tilt and movement of the Earth
- Over the continents, the ITCZ is further in the North because land is heated up more and faster
- Over the oceans, the position of the ITCZ doesn’t change much due to the high specific heat capacity of water (e.g. over the Atlantic Ocean)
Coriolis Effect
Any moving body in the Northern Hemisphere deflects to its right. Any moving body in the South Hemisphere deflects to its left.
Explaining Variations in Temperature, Pressure and Winds
1) Latitude
2) Distribution of Land and Sea
3) Sea Currents
Latitude (explain how it causes variations in temperature, pressure and wind)
Areas that are close to the equator receive more heat than areas that are close to the poles. This is due to two reasons:
1) Insolation is concentrated near the equator but dispersed near the poles.
2) Insolation near the poles has to pass through a greater amount of atmosphere and there is more chance of it being reflected back out to space.
Distribution of Land and Sea (explain how it causes variations in temperature, pressure and wind)
This is mainly due to the difference between specific heat capacities of land and ocean.
Water heats more slowly because:
- It is clear, so the sun’s rays penetrate to a greater depth (distributing energy over a larger volume)
- Tides and currents cause the heat to be further distributed
Distance from sea has an important influence on temperature. In winter, in mid-latitudes, sea air is much warmer than the land air, so onshore winds bring heat to the coastal lands. By contrast, during the summer, coastal areas remain much cooler than inland sites.
Sea Currents (explain how it causes variations in temperature, pressure and wind)
The effect of ocean currents on temperatures depends upon whether the current is cold or warm. Warm currents from equatorial regions raise the temperatures of polar areas (with the aid of prevailing westerly winds). However, this effect is only noticeable in the winter. For example, the North Atlantic Drift raises the winter temperatures of Northwest Europe.
Factors affecting Air movement
1) Pressure and Wind
2) Pressure Gradient
Pressure and wind (factor affecting air movement)
The main cause of air motion is the unequal heating of the Earth’s surface. The major equalising factor is the transfer of heat by air movement. Variable heating of the Earth causes variations in pressure and this in turn sets the air in motion. There is thus a basic correlation between winds and pressure
Pressure Gradient (factor affecting air movement)
Air blows from high pressure to low pressure. Globally, very high-pressure conditions exist over Asia in Winter (December) due to the low temperatures. By contrast, the mean sea-level pressure is low over continents in summer.
Specific Heat Capacity
The amount of heat needed to raise the temperature of a body by 1 degrees celsius
Great Conveyer Belt
a constantly moving system of deep-ocean circulation driven by temperature and salinity. The great ocean conveyor moves water around the globe
Transfer of Energy around the world
- 80% by wind
- 20% by ocean current
North Atlantic Drift Location
Warms up the temperatures at North West Europe
