Weather & Climate: Theory Flashcards
(37 cards)
Troposhpere
Lowest layer.
11 - 12km on average (8km at poles, 17km at equator).
-6.5°C decrease per km altitude increase.
Convection currents allow for weather.
Air pressure 200 - 1000mb.
Stratosphere
Troposphere to 50km.
Air pressure 20 - 200mb
High concentration of ozone causes a temperature inversion.
Stable conditions.
Mesosphere
From stratosphere to 80 - 90km. Air pressure 1 - 20mb. Temp decrease with altitude. 99.9% of the atmosphere's mass is below this layer. No ozone.
Thermosphere
From Mesosphere to space.
Air temperature can rise to 1000°C due to UV radiation, but sparsity of molecules decreases the ‘feel’ of temperature.
Air pressure < 1mb.
Latent Heat
Radiation
Sensible Heat
Conduction & Convection
Wind
The horizontal movement of air on the Earth’s surface. Winds always blow from areas of high pressure to areas of low pressure.
The Pressure Gradient
The gradual change of pressure over an area, shown on a weather map using Isobars.
Isobars
Lines made by joining points of equal atmospheric pressure together.
Hadley Cells
Basis of tropical air circulation.
Responsible for rainforest and desert climates.
0-30°N and 0-30°S, either side of the Inter-Tropical Conversion Zone (ITCZ).
Coriolis effect bends wind to the right, creating NE & SE trade winds.
Ferrel Cells
Responsible for mid latitude climates.
30-60°N and 30-60°S.
Warmer air from the tropics meets cold air from the poles at 60°, causing Cool Temperate climates.
Polar Cells
60°N+ and 60°S+.
Winds travel outwards from high pressure poles.
Subtropical Anticyclone
Meeting of Hadley and Ferrel Cells.
Mid-Latitude Depression
Meeting of Ferrel and Polar Cells.
Problems With The 3 Cell Model; 5 Factors Which It Ignores
Anticyclones. Depressions. Jet Streams. Trade Winds. Rotation of the Earth.
Impact Of Latitude: Daylight Hours
In the tropics, both day and night last about 12 hours all year round.
The further a place is from the equator, the more varied the lengths of day and night are.
At the poles, the sun doesn’t set during the summer and doesn’t rise during the winter.
Impact Of Latitude: Angle Of Incedence
The sun’s rays are concentrated in the tropics because the midday sun remains high in the sky all year round.
As you move further from the equator, the angle of incedence gets lower and the sun’s rays lose energy as they must travel further and are more spread out.
The equator therefore recieves more insolation in a year than the poles.
Gyre
A circular pattern of currents e.g. South Equatorial and Benguela (SAtlantic Ocean).
Why Are Gyre Patterns So Similar?
They are initiated by the same factors:
- Prevailing wind.
- Atmospheric circulation.
- Coriolis effect.
Dominant Ocean Currents
Western sides of gyres e.g. EAC.
Weaker Ocean Currents
Eastern sides of gyres e.g. Humbolt.
Coriolis Force
The turn of the Earth causes currents to turn to the right in the North, and to the left in the South.
Thermohaline Circulation
The formation of ice increases the salinity of water.
Saline water is more dense so it sinks.
This cold water travels from the poles to the equator.
At the equator, less salty water is less dense so it rises.
This warmer water travels back to the poles, completing the cycle.
What happens to air when it rises?
It becomes less dense and expands, causing the air temperature to fall.
