Atmosphere Notes (and Essays)

POINT TWO:
The unequal heating of the earth’s surface leads to an energy/heat imbalance.
• Locally speaking, to maintain some liveable balance, an area will have its own set of DAY/NIGHT processes
o DAY
 1. Incoming solar radiation arrives at the surface.
• Some of it will have been absorbed, scattered or reflected by the atmosphere before it hits the surface.
 2. Reflection of some of the Insolation happens at the surface.
• Depending on the albedo (The fraction of insolation reflected from the Earth back into space)of the surface (lighter surface, higher albedo) more or less insolation is reflected.
o The more reflection, the less energy absorbed.
o Reflection reduces heat energy at surface
 PROTIP: Know some albedo rates to quote in an exam.
 3. The Insolation that is not reflected by the surface and atmosphere is absorbed by the earth surface (around 46%).
• This absorption by the surface heats the surface and slowly flows from the warmer areas on the surface, to the cooler areas beneath.
o Depending on TYPE & NATURE of the surface, the heat will be transferred quicker or slower
 Loose sand for example is a poorer conductor of heat, and the top layer of sand will be far hotter than the lower layers- think about digging in sand on a beach.
• The transfer/movement of heat from the surface to the subsurface reduces heat at the surface, as heat moves from warmer areas to cooler areas.
 4. The absorbed insolation also causes water to heat up and as a result, to evaporate.
• This evaporation process ABSORBS HEAT from the environment (this absorbed heat is a Latent heat transfer)
o LATENT HEAT is the energy given off or absorbed by a system (in this case the water) where the temperature of the system (in this case the water) does not change.
o The temperature AROUND the system may change however due to heat being absorbed. (a balance!)
 5. Sensible heat is heat energy transferred between a surface and air where there is a difference in temperature between them.
• It is a noticeable temperature change (one you can feel).
• Sensible heat is transferred in 3 ways:
o Convection: The heat transferred by a fluid (liquid/gas – ie: air) – this heat continually moves from hot to cold.
o Conduction: The heat transferred from direct contact – metals will conduct better.
o Radiation: The heat radiated/given off by infrared waves.
o THINK OF A FIRE or different types of house heaters for each type.
 6. Long wave radiation is eventually radiated by the surface of the earth.
• WHY?
o Warm objects give off radiation.
o The hotter the object, the shorter the wavelength.
o The sun gives off short wave radiation, because it is so hot.
o The earth gives off long wave radiation, because it is heated by the sun.
 When the earth gives this LWR off, it is actually LOSING heat energy.