Which has highest albedo?
GEO 101, March 11, 2014
A
B
General review
Review adiabatic processes
Types of lifting
Latitudinal distribution of precipitation
Is it day or night?
If this is an isobar map, which winds are the fastest?
Warm
80
60
40
20
0
Cool
Which one is a high pressure?
Is it a high or a
low?
Which
hemisphere?
1
Ocean gyre, which
hemisphere?
What is the weather like in southeast Asia?
What month is this? January or July?
LAPSE RATES
Normal (environmental) lapse rate = temperature
structure of the atmosphere
Adiabatic rates = temperature changes in a rising
(cooling) or falling (warming) parcel of air.
Dry adiabatic lapse rate = no condensation, parcel
temperature stays above dewpoint
Wet (saturated) adiabatic lapse rate = condensation is
occurring in parcel
Descending parcels warm at the dry adiabatic rate.
Parcel will only rise if it is warmer than the surrounding
air!
Types of atmospheric lifting
Precipitable water vapor by latitude
cm
Frontal = warm goes up over cold air
Convective = bubbles of warm wet air
Orographic = up a mountainside
Convergent = air meets in a LOW
Capacity of air to hold moisture directly related to temperature
2
Latitudinal variation in precipitation
AIR MASS: large mass of air with similar temperature
and moisture characteristics forms over source region
and takes on characteristics of that region.
Air mass nomenclature
First letter is lowercase
Tells if air mass formed over land or water
c = continental = dry
m = marine = moist
Be able to explain this pattern in terms of capacity
of the air to hold moisture and lifting mechanisms
of lack of lifting mechanisms.
Major air masses
mT = marine Tropical
Major air masses
cT = continental Tropical
Second letter is uppercase
Tells latitude air mass formed in
T = Tropical = warm
P = Polar (40° - 60°) = cool
A = Arctic = cold
Major air masses
mP = marine Polar
Major air masses
cP = continental Polar
3
Major air masses
cA = continental Arctic
≈ 60° N
≈ 30° N
Front: the boundary between air masses
Front: the boundary between air masses
Looking from the top
Air mass #1
Air mass #2
Air mass #1
Air mass #2
Looking from the side
Cold front
Fronts are named for air mass that is “winning” the
pushing contest
Cold front: cold air mass is pushing warm one back
Warm front: warm air mass is dragging the cold one back
Frontal boundary symbols tell what kind of front and
direction of movement
Cumulus clouds
Direction of
movement
Possibly heavy rain
Moves quickly
Rapid temp. and
pressure changes
Narrow front
4
Warm vs. cold front
Warm front
2000 km / 1250 miles
Note frontal shape and scale difference between these
Direction of
movement
Stratus clouds
Drizzle
Moves slowly
Gradual temp. and
pressure changes
Wide front
Stationary front: neither air mass is “winning”
400 km / 250 miles
Occluded front: both air masses going same
direction, cold overtakes warm
Development of an occluded front
5
http://www.weather.com/maps/news/forecasts
ummary/uscurrentweather_large.html
Descriptive
terms
Wind
arrows
Latitude
Surf.Press.
Why?
Precip.
Why?
90ºN
60-90ºN
60ºN
30-60ºN
30ºN
0-30ºN
0º
0-30ºS
30ºS
30-60ºS
60ºS
60-90ºS
90ºS
6