Atmospheric heat budget

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  • Created by: khiggs1
  • Created on: 12-10-16 19:07
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  • Atmospheric heat budget
    • Heat transfer
      • Horizontal heat transfer
        • 80% of heat transferred away from tropics & carried by winds e.g.j et streams or depressions or hurricanes
        • 20% moved by ocean currents polewards
      • Vertical heat tranfer
        • From warmer surface of the Earth vertically
          • Conduction , radiation, convection and a little bit of latent heat
        • e.g. latent heat is needed to change water(ocean) into vapour which may rise until it condenses much higher (cloud)
          • Causes precipitation which will release energy and warm up the atmosphere
    • Factors affecting insolation
      • Short term effects
        • Seasonal Change
          • Insolation is equally distributed in each hemisphere in autumn and spring equinoxes - overhead the equator
          • In summer and winter solstices the sun is overhead the tropics maximum insolation are in the noth and south hemisphere
        • Diurnal change
          • The length of day and night varies in locations away from the equator
          • Polar regions - no insolation during winter when the region is tilted away from the sun
        • Local
          • Aspect
            • Slopes alter the angle at which the sun strikes Earth - South facing slopes
          • Urbanisation
            • Urban surfaces tend to absorb more heat
          • Cloud Cover
            • Can reflect absorb insolation but can also act as an insulating blanket which can cause either a rapid fall or increase in temperature depending on the conditions
      • Long term effects
        • Prevailing wind
          • The air mass is determined by the area that it has passed
          • Wind blowing over the sea tend t be cooler in summer and warmerr in winter
          • Mainly westerly
        • Proportion of land and sea
          • Land heats up quicker
            • Sea is low of density and increased specific heat capacity
        • Ocean currents
          • Caused by influence of prevailing winds
          • Warmer currents migrate pole wards + cold currents replace them
            • Gyre - circulatory motion
          • North hemisher - move clockwise opposite for south
            • Cause currents to go west- north Atlantic drift + Gulf stream
        • Altitude of the sun
          • At higher latitudes the energy from the sun pass through more atmosphere
            • Less concentrated d curvature of Earth , heating more land compared to the equator
        • Ocean conveyor belt
          • Transfer of cold water from the polar regions to the equator
          • The movement of less salty and less dense effect the temperature of the North Atlantic
        • Altitude of land
          • Insolation heats surface, warms the air above
          • Higher land is further away from heat source
            • The main mass of land is heated by insolation meaning higher land is cooler
          • The density decreases with height adding to cooling effect
    • Solar Energy Budget
      • Insolation - 100%
        • Long wave - 66%
      • Absorbed
        • 14% atmosphere
        • 51% Earth
      • Reflected
        • 27% Clouds
        • 2% Earth
        • 6% Atmosphere
        • Albedo - 35%
      • Radiated
        • 58% Atmosphere
        • 8% Earth
      • Evaporation
        • 26% Earth
      • Convection & Conduction
        • 8%
    • Global Heat Budget
      • The Earth isn't heating up or cooling down, there is a balance of short wave and long wave radiation
        • Look at a diagram
      • Although energy is lost through radiation , the net gain radiation not experienced in the poles
        • In polar regions there is a net deficit(loss)(negative heat balance)
          • In lower latitudes there is a net gain
      • The imbalance of heat transfer can be explained by many heat transfer (link)
    • Amount of energy received from the sun
      • Solar constant- rate of which energy reaches the Earth's surface from the sun
      • Distance from the sun- the orbit of the Earth can cause up to 6% variation in solar constant
      • Altitude of the sun in the sky - The equator is more heated as the Sun strikes the Earth head on but in the poles it is at a more oblique angle(curvature of Earth)
      • Length of day & night- Curvature of Earth/tilt means that the poles receive no insolation at certain times of years
    • Albedo - ratio between amount of incoming and reflected radiation
    • Insolation - short wave and when reflected of Earth - long wave radiation

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