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DIRT > Atmospheric Pressure/Wind - Chap 5 > Flashcards

Atmospheric Pressure/Wind - Chap 5 Flashcards

1
Q

Atmospheric pressure

A

force exerted by weight of gas molecules on unit of area
exerted equally in all directions
Basically weight of all gas molecules above you, more gas molecules above you at lower altitude –> higher pressure

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2
Q

Ideal gas law

A

P = pRT
p (rho) = density
R = constant
T = temp
*increase in temp –> increase in pressure
increase in density - increase in pressure

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3
Q

Density of gas

A

changes easily with location bc gas can expand as far as pressure allows

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4
Q

Increase in temp

A

higher pressure –> more energetic collisions btwn molecules

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5
Q

What is air pressure influenced by

A

temp, density, dynamic influences

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6
Q

dynamic factors influencing air pressure

A

vertical movement of air (air goes up = low pressure, air goes down = high pressure)

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7
Q

dynamic high vs low, thermal high vs low

A

dynamic high = strongly descending air -> high pressure
dynamic low = strongly ascending air -> low pressure
thermal high = cold surface conditions cause high pressure at surface
thermal low = warm surface conditions cause low pressure at surface

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8
Q

Isobars

A

show isolines of equal pressure,
circular/oval areas = high or low pressure zones
high + low is relative to area around it

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9
Q

ridge

A

elongated area of high pressure

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10
Q

trough (think depression/lower)

A

elongated area of low pressure

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11
Q

pressure gradient

A

shown by closeness of isobars –> closer together = more abrupt pressure change

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12
Q

Updrafts vs downdraft, ascents vs subsidences

A

updraft/downdrafts = small scale vertical motion of wind
ascent/subsidence = large scale vertical motion of wind

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13
Q

Cause of wind

A

unequal warming of Earth’s surface
ideally moves from high pressure to low pressure BUT wind rarely does that bc of Coriolis effect

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14
Q

3 factors affecting wind direction

A

1) Pressure gradient force
2) Coriolis effect
3) friction

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15
Q

Pressure gradient force on wind direction

A

air moves from high to low pressure air

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16
Q

Coriolis effect on wind direction

A

1) deflects right in Northern, left in Southern
2) deflection strongest at poles, almost 0 at equator
*acts at a 90 degree angle (to right in North, to left in South)

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17
Q

Geostrophic wind

A

where pressure gradient = Coriolis effect
In upper atmosphere wind moves PARALLEL or NEARLY parallel to isobars

18
Q

Friction effect on wind

A

mainly in lowest portions of troposphere
reduced Coriolis effect bc of drag of Earth’s surface –> causes wind to go btwn 0-90 angle of isobars

19
Q

Friction layer

A

extends only to 1000 meters, after that winds follow geostrophic or near geostrophic course (almost parallel)

20
Q

Anticyclone vs cyclone

A

anticyclone = high pressure center
- frictional zones = DIVERGES
cyclone = low pressure center
- frictional zones = CONVERGES

21
Q

4 patterns of anticylonic circulation

A

1) Upper atmosphere of Northern hem = moves clockwise in geostrophic manner (parallel to isobars)
2) friction layer (low altitude) North = DIVERGENT clockwise flow, so air spirals out + away from center
3) Upper atmosphere of South = moves COUNTERCLOCKWISE in geostrophic manner
4) Friction layer south = divergent COUNTERCLOCKWISE flow, so air spirals out + away from center

22
Q

4 patterns of cyclonic circulation

North - bad weather - not norm - counterclockwise

A

1) Upper atmosphere Northern Hem = moves COUNTERCLOCKWISE in geostrophic manner (parallel to isobars)
2) friction layer (low altitude) North = CONVERGING COUNTERCLOCKWISE flow, so air spirals out + away from center
3) Upper atmosphere of South = moves CLOCKWISE in geostrophic manner
4) Friction layer south = CONVERGENT CLOCKWISE flow, so air spirals out + away from center

23
Q

Vertical movement in cyclones + anticyclones

A

air descends in anti-cyclones (clear weather)
–> DIVERGES from air and goes towards ground, increasing pressure on ground
air rises in cyclones (cloudy + stormy)
–> CONVERGES from ground into cyclone + continues rising, so the pressure on ground is low

24
Q

What are Hadley cells

A

Warm air at equator rises (creates low pressure at surface)
reaches great heights + cools by the time it hits upper troposphere
air moves north/sound
descends at 30 N/S
goes back to equator as trade winds

25
Q

What are the 8 components of general circulation

A

1) Intertropical convergence zone (ITCZ)
2) trade winds
3) subtropical highs
4) westerlies
5) jet streams (upper troposphere winds)
6) polar front (subpolar lows)
7) polar easterlies
8) polar highs

26
Q

Subtropical Highs

A

Gigantic anticyclones off the west coast of the continents
*intensified cells of high pressure that extend about 30 latitude

27
Q

Weather in Subtropical highs (STH)

A

weather is always clear, warm, dry, calm
- absence of wind + regions called horse latitudes
- anticyclonic
SOURCE OF TRADE WINDS + WESTERLIES

28
Q

Trade winds

A

Cover latitudes 25 N to 25 S
prominent over oceans + interrupted over landmasses
generally easterly winds (blows from east)
winds named from direction they blow

29
Q

why are trade winds called trade winds?

A

extremely consistent in direction + speed
used by merchants to go from Europe to Americas
hold a lot of moisture –> tremendous potential for storminess + precip.

30
Q

Intertropical Convergence Zone

A

Zone where air from Northern hemisphere meets with southern (also called doldrums)

31
Q

Weather of ITCZ

A

convergence + weak horizontal airflow –> feeble and irratic winds
high rainfall, instability, rising air of Hadley

32
Q

Westerlies

A

predominant wind system of midlatitudes
btwn 30 + 60 N/S (less extensive than trades)
**Not as constant as trades bc easily interrupted by surface friction, topographic barriers, etc. SO not always blowing from west*

33
Q

Jet Streams

A

Polar front jet stream = near poles 9-12 km above surface
Subtropical jet stream = closer to 30 degrees N/S (higher altitude than polar)

34
Q

Rossby Waves

A

meandering curves of Jet stream
generally 3 - 7 rossby waves in jet streams

35
Q

Polar Highs

A

High pressure cells over both polar regions (contributes to very cold temperatures in Antarctic)
typically anticyclonic

36
Q

Polar easterlies

A

Formed by polar highs, btwn polar highs + 60 altitude
Cool + dry BUT variable

37
Q

Polar Front

A

Meeting zone btwn polar easterlies + warmer westerlies
characterized by rising air, widespread cloudiness, precipitation

38
Q

Effects on general circulation of atmosphere caused by seasons

A

1) during northern hemisphere summer = all components displaced northward
2) during southern hemisphere summer = all components displaced southward
displacement greatest at low latitudes + least in polar regions
shift caused bc of variations in surface warming

39
Q

What are Monsoons

A

Monsoon winds = unusually large latitudinal migrations of trade winds
*Himalayas play large role

40
Q

2 major monsoon systems + 2 minor

A

2 major = South + East Asia
2 minor = Australia + West Africa

41
Q

Causes of monsoons

A

Unequal warming of continents + oceans

From Google AI answer:
Summer Monsoon: As land heats up faster than water in the summer, warm air rises, creating an area of low pressure. This area of low pressure pulls in cooler, moist air, which leads to heavy rains.
Winter Monsoon: In the winter, water off the shore of a land mass heats up and rises, creating an area of low pressure. This area of low pressure pulls in dry air from over the land mass towards the water.

42
Q

Why is there an equatorial trough + polar high?

A

Around equator –> air is heated much more cuz more insolation SO the air rises + creates low pressure zones below
Around poles –> air is much colder, denser, so sinks down + increases pressure

DIRT (13 decks)

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