EE18 Flashcards
What are climates affected by?
Latitude Altitude Aspect Martime *climates determine hear moisture and sunlight available*
What happens to intensity of light with increasing latitude?
Intensity is radiation per unit area
Area over which radiation is received increases with latitude, thus intensity decreases with increasing latitude.
INTENSITY IS INVERSLEY PROPORTIONAL TO THE COSINE OF LATITUDE.
What is a weather front?
boundary seperating 2 masses of air of different densities.
Why is it colder closer to the poles?
The suns rays hit the earth perpendicularly at the equator.
North/south of this the suns rays are steeper.
The amount of atmosphere rays must pass through increases towards the poles.
Therefore more radiation is reflected and absorbed per unit area before it reaches the surface.
Why do clouds form?
Solar radiation heats up the earths surface.
The surface warms and emits IR to the atmosphere.
Differences in heating of different parts create pockets of warm air surrounded by cooler air.
Warm air is less dense and so rises =uplift
As the warm air rises is expands as there is less atmospheric pressure.
This expansion cools the rising air.
The cooler air cannot hold as much water vapour.
Water condenses to droplets- clouds.
What is subsidence?
The tropics receive the most precipitation of any area as they get the most solar radiation therefore the most surface heating. Therefore the most uplift of air and cloud formation.
This uplift creates a band of low atmospheric pressure relative to north and south.
When air rising reaches boundary between troposphere and stratosphere it flows towards poles.
Poleward moving air exchanges heat with the surrounding air and cools.
Once at a temperature similar to surrounding atmosphere it descends. This descending is subsidence and is the opposite of uplift.
What affect does subsidence have?
Subsidence creates regions of high pressure at lattitudes 30 degrees North and South, which inhibits precipitation -cloud formation. = horse lattitudes.
This is where most deserts are found.
What is the Hadley Cell?
Tropical uplift of air creates large scale atmospheric circulation in each hemisphere
What is the Ferrell cell?
Exists between the Hadley and Polar cells and driven by movement of Hadley and polar cell and exchange of energy between tropical and polar air masses.
What is the Polar Cell?
Cold dense air subsides at poles and moves towards equator when it reaches earths surface.
The descending air is replaced by air moving through the upper atmosphere from lower altitudes.
What does subsidence at poles cause and what is the consequence of this?
Subsidence at poles causes high pressure, therefore there is little precipitation in polar regions, despite ice and snow.
What do the 3 atmosphere circulations establish?
The three climatic zones
30 degrees N/S = tropical
30/60 degrees N/S = temperate
60* N/s = polar
What causes prevailing winds?
wind flows from areas of high pressure to areas of low pressure.
areas of high and low pressure are formed by atmospheric circulation cells which give rise to consistent movement at earths surface.
=prevailing winds.
What is the Coriolis force?
The earth is moving around its axis from west to east.
The speed of the atmosphere is faster at the equator.
Northward flowing air moving away from the equator is deflected to the East.
Southward flowing air moving away from the equator is deflected to the west
What phase is the earth currently in and what is this characterised by?
A cool climatic phase.
characterized by regular periods of cooling glacial formation and advance and the reverse.
What are milankovitch cycles?
The suggested caused for the interglacial cycles that occur at frequencies of about 100,000 years.
= combination of regular changes in the shape of the earths orbit and tilt of the axis - changes the intensity of solar radiation at high altitudes.
How does the earths orbit change, and what effect does this have?
Earths orbit shifts between circular and elliptical shape in regular cycles (100,000 years)
In elliptical there is a greater distance from the sun at aphelion which means less solar radiation = climate change.
Why are there colder climates at higher elevations?
atmospheric pressure and therefore air density decrease with increasing elevation.
Fewer air molecules to absorb IR
The air expands as it rises which leads to more heat loss and temperature falls at 10 degrees per km. = dry adibatic lapse rate.
water condenses as air cools and gains heat of condensation =moist adiabatic lapse rate = 6 degrees per km.
What is the lapse rate?
Decreasing temperature with increasing altitude.
How often does the angle of the earths tilt change and what effect does this have?
changes in regular cycles of about 41000 years.
-greater the angle of tilt, greater the seasonal variation.
When do sun spots occur?
Sun spots occur in 11 year cycles and are connected with other solar events like solar flares and solar weather
What classifies biomes?
Whittakers climatic community.
average annual temperate/average annual precipitation =
What is albedo?
solar energy reflected back into space
eg. snow increases albedo.
What happens to the effect of aspect with altitude?
effect of aspect increases with altitude.
eg. opposite sides of a hoof print have different microclimate.
