Mid-latitude Climates

Marine West Coast Climate

UK Air Masses

Air mass typesm = maritime, wetc = continental, dryP = polar, coldT = tropical, warmAmPcPmTcT

UK WeatherWesterly 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 depres sion (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

Westerlies bring damp air, uplift by Rockies.

Sub-tropical high, descending, dry air.Wind from east.

North American rainfallNorth American rainfall

Warm damp air from Atlantic. Hurricanes.

Mid-latitude Cyclones

Warm Front

precipitation

Cold Front

Cold air Warm air

Note difference in wind direction and how cold air advances under the warm sector

Polar front

Mid-latitude frontal zone

Cyclogenesiscold air

warm air

polar front

warm frontcold front

Dissolving stage

occluded front

Open stage Occluded stage

Early 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