Global Energy Budget

• Atmospheric Energy

  • Open system
  • Energy excess in the tropics
  • Deficit towards poles
• Atmospheric transfers

  • Ocean currents
  • Wind systems
  • Done by sensible heat transfers (war air masses/ocean water) and latent heat (hurricanes)
• Global Wind Systems

  • Trade winds - from STHP towards equator
  • Mid-latitude westerlies - From STHP towards poles(stronger in S hemisphere due to lack of land)
  • Polar Easterlies - from polar high pressure zones towards mid latitudes
• Sea Currents

  • Warm currents from equator increases temp of polar regions
  • Gulf Stream - Heat Northwards then Eastwards across N Atlantic = warmer European winters & cool summers
  • Labrador Current - Reduces summer temps - only if wind blows from sea to land
• Seasonal Variations in Temperature

  • Opposing North & South Hemisphere
  • Reflect general decrease in insolation from equator to the poles
• Seasonal Variations in Pressure

  • N hemisphere - greater contrasts
  • S hemisphere - more stable
  • Due to unequal land distribution - oceans more equal
• Sub—Tropical High Pressure Belts (STHP)

  • S hemisphere = 30* Latitude
  • N hemisphere = less continuous at 30*
  • Over oceans = high pressure in cells - Azores & Pacific Highs
• Pressure contrasts in S Asia & SW USA

  • high in winter
  • Low in summer due to overheating
• Equatorial Trough

  • 1008-1010mb
  • Max Insolation
  • July = N of equator
  • January = less S of equator - land mass can’t displace it as much
• Wind Belts

  • Intertropical Convergence Zone (ITCZ)
  • N in June - greatest variation over large land masses
  • Monsoon
  • Induced by Asia
  • Winds blow outwards from high pressure in Winter and inwards from low pressure in Summer
  • Reversal of land & sea temps
• Distribution of Land & sea

  • Different Specific Heat Capacities
  • 5x more for sea
• Ocean Currents

  • Prevailing winds blowing steadily cross the sea
  • Clockwise in NH, Anti-clockwise in SH
  • El Nino Events - warm surface water in east with cold in the west
  • Warm causes low pressure - movement of water from cold to warm
  • Winds push warm surface water to warm region, exposing cold water