pressure helps determine what 2 things
speed and direction
T/F
Winds always blow from high to low pressure
true
Horizontal differences in pressure leads to _____
winds
What is the average pressure value at sea level?
1013 IMP
T/F
Boiling point lowers as elevation increases
true
At most latitudes (except the equator), upper-level winds are _____________
westerly
What is the first rule of upper-level winds?
the westerly movement is caused by a temperature contrast between the Poles and equator
Higher pressure exists over the _____________ and lower pressure exists over the _________
equator, poles
Why westerly and why blowing from equator to poles?
1. more expansion of the equatorial column than polar column/ temperature factor
2. high pressure near equator at same altitude compared to poles
3. winds always are named based on the direction they come from - coriolis force deflection to the right
wave like motion in westerlies
rossby waves
- important impact on weather
- transport warm and cold air
- may affect upper-level divergence and convergence
- mechanism for cloud development and precipitation
rossby waves
high speed winds within upper-level westerlies
found near tropopause
jet stream
the 2 important jet streams:
polar front and subtropical front
newton's 1st law:
an object at rest will remain at rest and an object in motion will remain in motion as long as no force is applied to it
newton's 2nd law:
Force = mass * acceleration
forces that affect wind
- pressure gradient force
- coriolis force
- friction
- centripetal force
initiates motion
affect direction of motion (high to low)
affects speed (greater PG = greater wind speeds)
pressure gradient force
- due to earth's rotation
- air in motion is deflected (northern hemisphere - to right, southern hemisphere - to left)
- only deflects air in motion
- magnitude proportional to wind speed
- strength varies by latitude (zero at equator, max at poles)
coriolis force
when there is a balance between PGF and CF
- winds flow parallel to the isobars
- found above 1000 m
- friction is not important
- assumptions: perfectly straight isobars and evenly spaced apart
geostrophic flow
directed towards the center of rotation
it is the force that makes a body follow a curved path
centripetal force
PGF < CF
anticyclones
supergeostrophic
PGF > CF
cyclones
subgeostrophic
the 3 cells of the wind model
(does not explain upper level winds well)
polar, ferrel, and hadley
winter monsoon in asia
when high pressure land systems move to low pressure sea areas
summer monsoon in asia
when high pressure sea systems move to low pressure land masses
Synoptic scale wind that flows down mountain slopes
warmed by compression
can be very fast (90 mph+)
Chinook (Foehn) Winds
most common during winter
increase average winter temperatures in western plains
chinook winds
hot, dry winds
common in the fall
can contribute to the spread of fires
santa ana winds
(example shows california)
what is the mechanism of day time land and sea breeze?
warm air moves from the land to the sea, cool sea breeze moves onto the land
what is the mechanism of nighttime land and sea breeze?
cool land breeze moves to the sea, warm sea air moves to the land
- during the day coastal air flowing toward the interior
- it lifted as it passes over the mountains
- get orographic cloud cover
effect of sea breeze over hawaii
daytime mountain and valley breeze
valley breeze moves up the mountatin
nighttime mountain and valley breeze
breeze moves down the mountain
- common along margins of antarctica and greenland ice sheets
- when high pressure snowy areas move down a high plateau to lower pressure areas
katabatic winds
turbulent eddie
dust devil
oceans cover ____% of earth's surface
71%
massive, ordered pattern of water flow
ocean current
- brings warm water to northern europe
- moderates climate along norwegian coast thus even in the winter the coasts of Norway are ice free
Gulf Stream
- along certain coastal areas, surface water drifts away from the coast
- deep, cold, nutrient-rich water from below rises to replace it (upwelling)
- it greatly influences sea surface temperatures and thus weather climate
- it also affects biological act
upwelling
Why are certain coastal areas so dry?
cold water upwelling, so dry cold air over land, least cloud formation, thus no/less rain
surplus energy transferred by atmosphere and oceans to higher latitudes
heat budget
cell that is 0-30 degrees N/S
Hadley cell
cell that is 30-60 degrees N/S
Ferrell cell
cell that is 60-90 degrees N/S
Polar cell
rising air from cells generates low pressure zones
ITCZ, polar fronts
sinking air from cells generates high pressure zones
subtropical highs
areas at latitudes where the air rises (the equator) have _____ precipitation than evaporation
more
areas of latitudes where the air descends have more _________ than precipitation
evaporation
weather is dominated by the Hadley cell
- small annual variations in temp
- seasons based on precipitation
- other influences: ITCZ, hurricanes, el nino
tropical weather and climate
What type of precipitation is caused by the ITCZ?
convective
Hurricanes have winds over how many MPH?
75 (34 m/s^-1)
other names for hurricanes
typhoons, tropical cyclones