Transcript Lecture 10/11

Mid-latitude Climates
Marine West Coast Climate
UK Air Masses
Air mass types
m = maritime, wet
c = continental, dry
P = polar, cold
T = tropical, warm
A
mP
cP
mT
cT
UK Weather
Westerly Unsettled weather with variable wind directions as depressions cross the
country. Mild and stormy in winter, generally cool and cloudy in summer
(mP, mPw, mT).
NW
Cool, changeable conditions. Strong winds and showers affect windward
coasts especially, but the southern part of Britain may have dry, bright
weather (mP, mA).
Northerly Cold weather at all seasons, often associated with polar lows. Snow and sleet
showers in winter, especially in the north and east (mA).
Easterly Cold in the winter half-year, sometimes very severe weather in the south and
east with snow or sleet. Warm in summer with dry weather in the west.'
Occasionally thundery (cA, cP).
SoutherlyWarm and thundery in summer. In winter it may be associated with a low in
the Atlantic giving mild, damp weather especially in the south-west or with a
high over central Europe, in which case it is cold and dry
(mT or cT, summer; mT or cP, winter).
Cyclonic Rainy, unsettled conditions often accompanied by gales and thunderstorms.
This type may refer either to the rapid passage of depressions across the
country or to the persistence of a deep depression (mP, mPw, mT).
Anticyclonic Warm and dry in summer, occasional thunderstorms (mT, cT). Cold and
frosty in winter with fog, especially in autumn (cP).
Effect of wind
direction and
topography on
rainfall in England
and Wales
Air masses in N. America
North American rainfall
Westerlies bring damp
air, uplift by Rockies.
Sub-tropical high,
descending, dry air.
Wind from east.
Warm damp air from
Atlantic. Hurricanes.
Mid-latitude Cyclones
Warm Front
precipitation
Cold Front
Cold air
Note difference in wind direction and how
cold air advances under the warm sector
Warm air
Polar front
Mid-latitude frontal zone
Cyclogenesis
cold air
polar front
warm front
cold front
warm air
Early stage
occluded front
Open stage
Occluded stage
Dissolving stage
Cyclogenesis – in cross-section
Conveyor belt model of cyclone
Mid-latitude Cyclones
Formation revisited
Polar front
Upper atmosphere pressure and winds
Mid-latitude Climates
Mediterranean Climate
Humid Subtropical
Humid Continental
High-latitude Climates
Sub-arctic Climate
Tundra Climate
Polar Climate