ENVS10001 Lecture Notes - Lecture 8: Shortwave Radiation, Oceanic Climate, Köppen Climate Classification
17 May 2018
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GLOBAL PATTERNS OF CLIMATE
• Climate: the long term weather patterns of an area, measured by radiation, wind, temperature,
rainfall and atmospheric pressure
• Population densities described by climate ! Monsoon in India
Fundamental Drivers of Global Climate
• The suns energy applied to an atmosphere, and
resulting in areas of rising (unstable, moist) + sinking
(stable, dry) air, on a:
Spherical Earth
• Radiation gives solar energy budget
o Sun emits shortwave radiation, earth reflects
50%, earth emits long wave radiation
• 23% of heat trapped in water vapour
• 51% heat in surface ! spread unevenly, hits vertically at equator + obliquely at poles
o Sunlight spread over different surface area at different latitudes
• Warming equator (convective energy redistribution) ! air rises up towards poles, then cools +
sinks down
• 0.65°C decrease per 100m rise (due to lower density of air = less molecule movement) or
220km north/south
o Decrease in temp = decrease in capacity to hold moisture ! creation of clouds/rain
Tilted Earth (Seasonality)
• 23.44° = tilt of the Earth, orbit = anti-clockwise looking down
• Higher latitude = greater seasonality
• Solstice: times of min/max sunlight hours in a day
• Equinox: times of equal sunlight + darkness in a day
• Time sun is overhead + surface area affected by sun ! drives seasons
Mix of Land + Water (Continentality)
• Continentality: tendency of land to experience more thermal variation than water due to
relatively lower heat capacity
• Continental climate ! dryer than oceanic climate
o Due to less moisture input to atmosphere from evaporation
• Oceanic currents ! driven by friction from atmospheric circulation ! redistribute heat which is
distorted by landmass
Solar Radiation
•Differential heating of the earth
•Albedo effect ! dark, wet soil reflects 5%, snow/ice reflects 40-95%
•Latitudinal gradient in energy absorption = pressure gradient
oHigh latitude = loss of radiation
oLow latitude = gain or radiation
Document Summary
Global patterns of climate: climate: the long term weather patterns of an area, measured by radiation, wind, temperature, rainfall and atmospheric pressure, population densities described by climate ! Fundamental drivers of global climate: the suns energy applied to an atmosphere, and resulting in areas of rising (unstable, moist) + sinking (stable, dry) air, on a: Spherical earth: radiation gives solar energy budget, sun emits shortwave radiation, earth reflects. 220km north/south: decrease in temp = decrease in capacity to hold moisture ! creation of clouds/rain, differential heating of the earth, albedo effect ! dark, wet soil reflects 5%, snow/ice reflects 40-95% Latitudinal gradient in energy absorption = pressure gradient. Solar radiation: high latitude = loss of radiation, low latitude = gain or radiation. Lumpy earth: not flat, 9km differences in elevation, orographic effect ! uplift = vertical temperature variation = rain shadow (tropical glaciers on equator)
