Climate Theory Introduction Document Reference: RTC-PRE_Climate_Theory_2018-001 Date of last revision: 20 Feb 2018

Definition of climate The statistical description in terms of the mean and variability of relevant quantities over a period of time ranging from months to thousands or millions of years. “Average weather” The classical period is 30 years, as defined by the WMO Temperature, precipitation, wind, etc Biomes

Factors influencing Climate Latitude (its influence on the amount of solar radiation received) *** Air mass influences *** Location of global high and low pressure areas (pressure belts) *** Heat exchange from ocean currents Distribution of mountain barriers Pattern of prevailing winds Location of land to the sea Altitude *** => Macro Level

Different Scales of Climate Regional climates Variety of different scales of climatic investigations macroclimate- largest area of study, area extends for 4 x 108 m2, up to 6000 m vertically (continental in scale) mesoclimate- 103 m2 up to 4 x 108 m2 in area (sub continental in scale) Local climate - a group of microclimates that characterize a specific region; 103 to 108 m2 in size Microclimate - the smallest category 1 to 104 m2 in area An individual field or park

Köppen climate classification system Annual and monthly averages of temperature and precipitation that generally coincided with world patterns of vegetation and soils. A - Tropical Moist Climates, where all months have average temperatures above 18°C B - Dry Climates, with deficient precipitation during most of the year. C - Moist Mid-latitude Climates with Mild Winters. D - Moist Mid-Latitude Climates with Cold Winters. E - Polar Climates, with extremely cold winters and summers.

Factors influencing climate

Latitude and its influence on the amount of solar radiation received.

Latitudinal Influence location of the overhead Sun at solar noon Inter-tropical convergence zone (ITCZ) – Uplift->clouds->Precip. Subtropical high pressure zone _ clear skies. Polar Front Uplift->clouds->Precip. Polar vortex _clear skies. Tropical/subtropical and polar air masses (Fronts). These respond to the seasonal movements of the Sun.

Air mass influences

Location of global high and low pressure areas Pattern of prevailing winds

Heat exchange with ocean currents

Distribution of mountain barriers Altitude

Location of land relative to the sea

Wet Dry Warm Cold Köppen climate classification system Grp I Grp II Tropical wet Tropical wet and dry Tropical dry (desert) Grp I mid latitude wet Mid latitude summer or winter dry mid latitude dry (desert) Grp II Polar wet Polar wet and dry Polar dry (desert) III