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Heating the Atmosphere and Ocean A. Heating the Atmosphere and ocean Most energy comes from Sun Energy transfer (all 3 involved in atmosphere/ocean) 1. conduction - transfer heat between adjacent bodies - works best in solids eg. rock minerals - air and water poor conductors 2. convection - movement in gas or liquid - heating causes that part to expand and rise - lower density - cooling cause part to contract, increase density and descend. 3. radiation - across space and through matter Energy Flow through the Atmosphere-Ocean Environment Insolation (IN coming SOLar radiATION) places on earth receive a fluctuating supply of energy because 1. 1. Spherical - sun directly overhead greater intensity - higher latitudes longer path to travel 2. 2. rotates on a tilted axis - insolation occurs from sunrise to sunset - seasonal variation in length of day and insolation - solstices - equinoxes 3. 3. elliptical orbit around the sun -earth closest to sun Jan and furthest away July passes through atmosphere and hits gases, dust, and clouds 1. 1. absorb - retention of radiant energy 2. 2. scatter - radiation bouces off in all directions 3. 3. reflect - bounces off in on direction - albedo of a surface is the proportion of insolation hitting it that is reflected Solar Energy and Earth’s Surface earth’s surface reflects or absorbs the insolation depends on surface material and their albedo 1. land - light (high reflection) ie. Albedo of snow 90% - dark (low reflection) ie. Albedo of blacktop 5% 2. ocean - albedo depends on sun’s angle - vertical albedo 3% - - 5 degrees over horizon albedo 50 – 80% - - oceans take longer to heat up and are slower to cool down than land Radiation from ground Terrestrial radiation – – more effective in heating the lower atmosphere than insolation – – temperature are higher near sea level than they are at altitudes of several thousand feet. – – Denser air near ground contains most of the dust particles, water vapor and other gasses that absorb heat Convection – causes warmed air in contact with the ground to rise Conduction – rocks, soil and water only conduct heat into few centimeters of atmosphere Lapse rate – rate at which temperature decreases with height environmental lapse rate – particular time place clam winds - 6.5C per km - can change because of differences in heating and cooling of ground Temperature inversion - cooling near ground on windless and cloudless conditions at night causes air 10s – 100s meter to be cooler than air above it Clouds play important role - absorb terrestrial radiation from below and radiate heat back - slow the return of heat energy to space and keep more heat in lower atmosphere - cloudy nights are warmer than clear nights Balance of Energy in the Atmosphere-Ocean Environment Heat Balance - Heat transfer by conduction, convection, and radiation maintains a balance of inputs from the sun and outputs from Earth. - keeps temperatures in the lower atmosphere at levels that do not fluctuate wildly. Global warming – – changes in the balance between insolation and outputs – – Greenhouse effect – – Increase in carbon dioxide, dust and water vapour that absorb terrestrial radiation might result in rising temperature in lower atmosphere – – Note: the atmosphere does not have barriers like a greenhouse NOR can the atmosphere be controlled. Global Distribution of Solar Energy Tropics – more energy arrives than is radiated back to space surplus Polar – radiate out more energy than arrives – deficit Balancing mechanism acts to maintain temperatures in different parts of world 1. 1. horizontal transfer of energy through convection - air heated in tropics moves poleward - oceans heated in tropics moves poleward. B. TEMPERATURE DIFFERENCES ON EARTH Isoterms – lines joining places of equal temperature - generally run along the parallels of latitude Water - Nearness to a large body of water - cool in summer - moderate in winter Altitude – temperature decrease with alititude Latitude – further away from the equator north or south the cooler it gets Prevailing winds - blowing over land – hot in summer and cold in winter Ocean Currents - warm currents and cold currents Continentality - high annual range of temperatures - ie. Hot in summer & cold in winter Human Activity – localized impacts but impact tiny on total atmospheric heating