Studied by 4 people
what heats the earth
solar energy heats the earth and generates winds which drive ocean currents
how is the atmosphere heated
from below, bc atm is particularly transparent to visible radiation directed at Earth from sun and absorbs very little of it
why does earth have seasons
bc tilted axis, different side has warmth for a certain amount of time
how much is earth tilted
23.5 degrees
vernal (spring) equinox
march 21, sun directly overhead at equator on equinox
autumnal equinox
sept 23, sun directly overheat at equator
summer solstice
june 21, sun stops at noon. sun directly over tropic of cancer, 23.5 degrees N lat
winter solstice
Dec 22, directly overhead tropic of capricorn. 23.5 d S lat
declination
angular distance of sun from equatorial plane (varies btwn. 23.5 degrees N and 3.5 d S lat
arctic circle
N of 66.5 D N lat. No direct solar radiation during N hemisphere
antarctic circle
S of 66.5 d S latitude
How is heat transferred from high and low latitudes
atmospheric winds and ocean currents
solar footprint
solar radiation is concentrated in a small area such as low latitude areas. in high lat areas, strikes at an angle therefore spread out
atmospheric absorption
atm absorbs radiation. thickness varies with latitude, high latitude has greater thickness
albedo
0-100% of incident radiation that is reflected back to the space. reflectivity is dependent on material, ice (high reflectivity)
physical properties of atm
transfers heat and water from place to place. complex relationships btwn. air comp, temp, density, water vapor content, pressure.
mostly N2 and O2, other gases significant for heat trapping properties
troposphere
lowest layer of atm. where weather occurs, temp decreases with altitude. extends from surface to 12km (7 mi).
convection cells
rising and sinking air. warm air rises (less dense), cool air sinks (more dense), moist air rises (less dense), dry air sinks (more dense
atm water vapor content
warm air is moist, cool air dry, water vapor less dense than air
atmospheric pressure
thick column of air at sea level. high surface pressure equal to 1 atm (14.7 pounds/in2). decreases with increasing altitude. thin column of air means lower surface pressure.
air movement
cool dense air sinks, high surface pressure
warm moist air rises, low surface pressure
what are the global air patterns
air rises at equator (low pressure), sinks at poles of high pressure, flows from high to low pressure.
coriolis
Gaspard Gustave de Coriolis: 1792-1843. rotating frame of reference, effects objects in motion in N Hemisphere to veer right of intended course, while it causes objects in S to veer left.
coriolis effect
inertial force that acts on objects that are in motion relative to a rotating reference frame.
circulation cell types
hadley cell, ferrel cell, polar cell
hadley cell
0-30 d latitude
ferrel cell
30-60 d latitude
polar cell
60-90 d latitude
high pressure zones
descending air. subtropical highs (30 d lat), polar highs (90 d lat)
low pressure zones
rising air. equatorial low (equator), subpolar lows (60 d lat)
trade winds
from subtropical high pressure to equatorial low pressure belt
NE trade winds
in N hemisphere, blows from NE to SW due to coriolis
SE trade winds
S Hemisphere, blows from SE to NW
prevailing westerly wind belts
from 30-60 d latitude, blows from SW to NE
polar easterly wind belts
60-90 d lat, blows from NE in N hemisphere and SE in S hemisphere
doldrums
intertropical convergence zone (ITCZ) at equator
horse latitudes
30 degrees
polar fronts
60 degrees
weather
conditions of atm at particular time and place
climate
long term average of weather
cyclonic flow
counterclockwise around low pressure cells in N hemisphere. clockwise around low pressure cells in S. Hemisphere
anticyclonic flow
clockwise around high pressure cells in N hemisphere. counterclockwise around low pressure cells in S hemisphere
sea breeze
land heats air around it, during afternoon, warm low density air over land rises. creates low pressure region over land, causing cool air over ocean to be pulled in.
land breeze
land to ocean. at night, land cools. cool high density air sinks, creates high pressure region, wind blows from land, late evening to early morning hours
storms
atmospheric disturbances with strong winds and precip
air masses
large volumes of air with distinct properties. land air masses: dry (contintental), marine air masses: moist (maritime)
polar maritime air masses
N Pacific and N Atlantic oceans, polar continental air mass that originates over canada
tropical maritime air masses
originate from tropical pacific and atlantic oceans and caribbean. tropical continental air mass that originates over mexico also affects US weather
fronts
boundaries btwn air masses
warm front
contact where warm air mass moves to colder area
cold front
contact where cold air mass moves to warmer area
jet stream
narrow fast moving easterly air flow. exist at middle latitudes below top of troposphere.
cyclones
large rotating masses of low pressure characterized by strong winds and torrential rain
hurricanes
N and S America
Typhoons
alternate name for hurricanes in N Pacific
Cyclones
Name of hurricanes in Indian Ocean
how do hurricanes originate
a. water evaporates, stored heat in form of latent heat of evaporation
b. water condenses, heat released, air rises
c. rising air decreases surface pressure, draws more moist air into storm
d. as air rises, cools, releases more heat, powers storm, feedback loop, intensifies
tropical depression
winds less than 61 km/ hour (38 mph)
tropical storm
sinds 61-120 km/hr (38-74 mph)
hurricane or tropical cyclone
winds above 120 km (74 mph)
saffir simpson scale
hurricane intensity further divides cyclones into categories based on wind speed
how many hurricanes happen/year
100 worldwide. conditions needed for formation of a tropical cyclone: warm ocean water > 25 d C supplying heat energy to atm by evap. coriolis affect causes spinning
when is hurricane season
June 1-Nov 30
eye of a hurricane
low pressure center. Diameter of a hurricane is less than 200 km (124 mi). larger hurricanes can be 500 miles
what other factors affect hurricanes
warm waters, wind shear, El Nino, La Nina
what is most destructive about hurricanes
high winds, intense rainfall, storm surge which can be up to 40 ft high.
historically destructive storms
Galveston TX 1900,
Andrew 1992
Mitch 1998
Katrina 2005
Ike 2008
Irene 2011
Sandy 2012
Hurricane Sandy
2012, Cat 1, largest Atlantic hurricane on record. 1100 miles wide. Storm surge coincided with peak high tides in heavily populated N. York and N. Jersey. Coastal erosion, flooding, 233 deaths, $68 billion in damages
2005 hurricane season
27 named storms, 15 hurricanes. Season extended to 2006 Jan. 5 cat 4+5 hurricanes. Dennis, Emily, Katrina, Rita, Wilma.
Hurricane Katrina
costliest and deadliest US hurricane. Cat 3 landfall in Louisiana. Largest of its strength to make landfall
Hurricanes Rita and Wilma
Rita: Sept 2005, most intense gulf tropical cyclone.
Wilma: Oct 2005, most intense hurricane in Atl. basin. multiple landfalls, affected 11 countries
ocean’s climate zones
equatorial, tropical, subtropical, temperate, subpolar, polar
tropical
N and S of equatorial, tropics of Cancer-Capricorn. strong trade winds, little precip, rough seas
equatorial
solar radiation high, rising air, weak winds, doldrums, rain, low salinity, tropical cyclone breeding ground
subtropical
high pressure, descending air, weak winds, sluggish currents
temperate
strong westerlies, severe storms, in N atlantic, fierce storms common
subpolar
extensive precip, summer sea ice
polar
high pressure, sea ice most of year
sea ice formation
forms directly from freezing seawater on ocean surface in contrast to icebergs that are pieces of a land based glacier.
slow water freezes easiest. needle like crystals become slush, slush becomes pancake ice and coalesces to ice floes
thick pressure ridges
ice floes thicken to form pressure ridges
icebergs
pieces of land based glacier that break away from glacier and float out to sea
shelf ice
thick floating sheets of ice formed when glaciers break into ocean
wind power
uneven solar heating generates winds, turbines harness it, offshore farms always generate electricity
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