Atmospheric circulation

Question 1

atmosphere

Answer 1

layer of gases and particles that envelops Earth

100 km compared to Earth’s radius (6,000 km) - thin

Question 2

troposphere

Answer 2

lowest, most important
75% of atmosphere’s mass and 99% of its water vapor and dust
almost all weather and clouds occur here
very turbulent

Question 3

stratosphere

Answer 3

middle layer
contains ozone layer
dry, no clouds, almost free from weather disturbances

Question 4

mesosphere

Answer 4

cold, tenuous
min temp approx. -100 deg C
upper part gives way to space

Question 5

composition of atmosphere

Answer 5

N2 (78.1%) and O2 (20.9%)
Ar, CO2, Ne, He, CH4
water vapor can occupy up to 4% of air volume

Question 6

drivers of air density

Answer 6

air has mass - 1cm^2 of dry air = approx. 1.04 kg
density decreases with temp, decreases with humidity, increases with pressure
warm air holds more vapor

Question 7

solar heating - received heat

Answer 7

about 50% of energy radiated toward Earth is absorbed
input energy from sun varies with transparency of atmosphere, albedo, angle of sun
varies with latitude - strikes high lats at greater angle = less directly
sunlight filters through more atm at high lats –> favors reflection of light
so, low lats receive more energy
varies with seasons due to tilt

Question 8

solar heating - re-radiated heat

Answer 8

high lats lose more heat to space than they gain heat; the opposite is true for low lats
ocean and atm move heat from low lats to high lats to compensate for that imbalance
- ocean circ accounts for 1/3 of poleward heat transfer, atm circ 2/3

Question 9

effects of solar heating on atmospheric circulation

Answer 9

differential heating between low and high lats
- powers air movement (convection current) between equator and poles
- low pressure at the equator and high pressure at poles
meridional circ of air (meridonial winds)

Question 10

coriolis effect

Answer 10

1.) Earth rotates eastward
2.) tangential velocity of a point on the Earth is a function of lat - velocity is essentially 0 at poles, max at equator
apparent deflection of the path of an object that moves within a rotating frame
- N hem turns counterclockwise, S hem clockwise
deflects the moving air of water from initial course
- air moving equatorward is deflected west

Question 11

circulation cells

Answer 11

Hadley Cells - tropics
Ferrel Cells - mid lats
Polar Cells - poles
within cells, air moving horizontally is associated with major winds, zones of fast horizontal motion of air masses from high to low pressure, surface winds strong and dependable
in between cells, ascending or descending air creates low and high pressure systems, convergence/divergence of air masses, weak and erratic surface winds
falling air is dryer - more evap than precip (desert/high salinity)
ascending air is humid - more precip (tropical climate)

Question 12

Intertropical convergence zone (ITCZ)

Answer 12

equatorial area at which trade winds converge
zone of rising air near equator - equatorial low
weak winds, quiet

Question 13

subtropical highs

Answer 13

zone of high atm pressure around 30 deg
falling air between Ferrel and Hadley cells
weak surface winds
aka horse lats

Question 14

trade winds (easterlies)

Answer 14

surface winds of Hadley Cells, centered about 15 deg lat

from NE in N hem and SE in S hem

Question 15

westerlies

Answer 15

surface winds of Ferrel Cells, centered around 45 deg lat

from SW in N hem and NW in S hem

Question 16

Polar easterlies

Answer 16

surface winds of Polar Cells, centered around 70 deg lat

from NE in N hem and SE in S hem

Question 17

weather vs climate

Answer 17

weather - state at a specific time and pace

climate - long-term statistical sum of weather in an area

Question 18

storms

Answer 18

local or regional amt disturbance

strong winds, often precip

Question 19

cyclones

Answer 19

huge rotating masses of low-pressure air in which winds converge and ascend
not the same as tornadoes

Question 20

air masses

Answer 20

large body of air with nearly uniform properties

tend to take on characteristics of surface below

Question 21

Large tropical cyclones

Answer 21

Hurricanes in N Atlantic and E Pacific
Typhoons in W Pacific
Tropical cyclones in Indian Ocean
Willi-Willis near Australia
At least 119 km/h winds
Around 100/year
Around 1000 km diameter and 15 km high
powered by heat from ocean
- air of tropical depression heated by ocean (>26 C)
- warmed humid air rises and condensation, precip begin
- strong winds converge circularly
- eventually dies out over land or cold ocean