Atmospheric pressure - world pressure belts Flashcards
what is atmospheric pressure?
the weight of the atmosphere on the surface of the Earth
how does temperature in air influence atmospheric pressure?
- high temp. air rises and expands and low pressure is formed. Air will now travel towards area that air left after rising.
- low temp. air contracts and sinks and high pressure is formed.
Explain the following picture
these are world pressure belts.
inner cells are called Hadley they are low pressured and rise at the equatorial low pressure belt or ITCZ they then sink and cause high pressure at the subtropical high pressure belt. (left to right)
after we get ferrel cells which rise at the subtropical high pressure belt and sink at subpolar low pressure belt . (right to left)
last are the polar cells which rise at subpolar low pressure belt and sink and polar high pressure belt
list the three cells (the tri-cellular circulation)
- Hadley
- Ferrel
- Polar
list the world pressure belts and where they found
- equatorial low pressure belt or ITCZ, 0*
- subtropical high pressure belt, 30* N or S.
- subpolar low pressure belt 60* N or S.
- Polar high pressure belts N or S
what does ITCZ stand for ?
Intertropical Convergence Zone
what is a dew point ?
temp. at which water vapour begins condensing.
given the term for the following:
intense heat at equator causes rapid uplift of hot, moist air resulting in very low pressure at surface.
equatorial low
why are thunderstorms and convection rain common in equatorial regions?
as air in equatorial low rises it cools dow at top and reaches dew point and when condensation starts taking place huge cumulonimbus clouds form.
at what height does air start diverging polewards?
10 000 meters
what are westerly winds?
wind that blows from subtropical belts to subpolar belts, or ferrel cell surface winds.
in S hemis. westerlies blow from NW and in N hemis. westerlies blows from SW.
what are front?
zone where two air masses of diff. temp. meet
