(7) geo: pressure gradient force and winds

what makes air move?

pressure

pressure

force applied over an area

how do we measure pressure?

barometer

what happens if you have more air on one side?

it will bounce back to the other side

entropic force

arises from entropy (the tendency towards disorder)

molecules/atoms move from

high pressure to low pressure

pressure gradient force in the atmosphere

air flows from high pressure to low pressure

isobars

lines of constant pressure

closer lines on a topographic map mean

more change in pressure in a shorter distance

smaller space between isobars leads to

steeper gradient

global pressure patterns

mirrored high and low pressure areas in the northern and southern hemisphere

aleutian and icelandic lows

dominate pressure patterns in the northern hemisphere

steep pressure gradient forces are in

northern hemisphere high latitudes

PGF’s in the atmosphere

make wind travel in straight lines from high to low

wind diverges in

high pressure areas

wind converges in

low pressure areas

why did the wind have curvature?

coriolis force

coriolis force

apparent deflection of winds because the earth is rotating, radius of earth’s axis rotation changes

coriolis force (2)

makes things like planes or current of air that travel long distances around earth appear to move at a curve opposed to a straight line

coriolis force causes wind to be

deflected

which way is wind deflected in the northern hemisphere?

to the right

which way is wind deflected in the southern hemisphere?

to the left

faster wind means

a stronger coriolis force

coriolis force acts which way in the direction of the PGF

opposite

what does the opposite direction cause the wind to do?

causes wind to flow perfectly parallel to isobars

what is geostrophic flow?

wind flowing perfectly parallel to isobars, ex: jet stream

rossby waves

wiggles in the jet stream

what do jet streams do?

meanders control midlatitudinal weather patterns

what do low pressure to the right of troughs develop?

develop cyclonic flow

what do high pressure to the right of ridges develop?

develop anticyclonic flow

cyclones

are around areas of surface low pressure

cyclones are

counterclockwise in NH, clockwise in SH

anticyclones

are around areas of surface high pressure

anticyclones are

clockwise in NH, counterclockwise in SH

the PGF + coriolis force does what to wind flow?

it predicts it to flow in perfect circles around areas of high and low pressure

friction

slows the wind down and reduces the strength of the coriolis force

pgf + coriolis + friction

friction slows the wind down, reduces the strength of the coriolis force, produces convergence around low pressure and divergence around high pressure

convergence occurs around

low pressure

divergence occurs around

high pressure

onshore and offshore breezes exist because?

air and land heat are at different rates

what do onshore and offshore breezes cause?

monsoons