Diurnal Energy Budgets

• Daytime Energy Budget

  • Incoming Solar Radiation (Insolation)
  • Reflected Solar Radiation (Albedo)
  • Surface Absorption
  • Sensible Heat transfer
  • Long-wave Radiation
  • Latent Heat transfer (evaporation)
  • Dew
• Incoming Solar Radiation

  • Main input
  • Increased cloud cover = less radiation that reaches Earth
• Reflected Solar Radiation

  • Albedo
  • Varies with colour
  • Grass = 20-30%
  • Concrete = 10-15%
  • Snow = 75-90%
• Surface absorption

  • Energy hits Earth & heats it up
• Sensible Heat transfer

  • Movement of parcels of air into and out of area
  • Eg. air warmed by surface may rise due to convection and be replaced by cooler air - convective transfer
• Long Wave Radiation

  • Radiation of energy from Earth into the atmosphere
• Latent Heat transfer - Evaporation

  • Heat energy used to turn liquid into gas
  • More water at surface = more used for evaporation = less used to raise local temperatures
• Dew

  • Condensation on a surface
  • Saturated air due to air temp decrease to cause condensation
  • Insolation in reradiated as long wave radiation - some absorbed by water vapour, increasing temp
• Night - time Energy budget

  • Longwave Radiation
  • Latent Heat transfer (condensation)
  • Sub-surface supply
  • Sensible heat transfer
• Sub-Surface supply

  • Heat transferred to the soil & bedrock during the day that is released back to surface at night
  • Partly offset night cooling