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Choose the correct words for this statement about atmospheric heating. Atmospheric heating mostly occurs (1) _____ the tropopause due to the greenhouse effect, which traps (2) _____ radiation.
  • A
    (1) above; (2) infrared
  • B

    (1) above; (2) ultraviolet

  • C
    (1) below; (2) infrared
  • D
    (1) below; (2) ultraviolet

Refer to figure.
The Sun provides the energy that heats the Earth and its atmosphere by a process of insolation (incoming solar radiation). This is short wave radiation in the form of light, ultraviolet, and many other parts of the electromagnetic spectrum.

After insolation has occurred, the surface of the Earth warms up, and produces longer wave radiation (infrared radiation), as well as conduction and convection, which heats the atmosphere from the ground.

The greenhouse effect is how the Earth manages to keep its heat in. The greenhouse gasses mostly allow the short wave radiation to penetrate down to the ground, but then keeps a lot of the longer wave radiation in, similar to a greenhouse, which lets shortwave radiation (sunlight) in through the glass walls, but keeps the long wave infrared radiation in to warm up the internal atmosphere for the plants.

If the Earth did not have any greenhouse effect, the atmosphere would get very cold, particularly during the night.

The greenhouse effect comes from the presence of many different gasses in the atmosphere, and include water vapour, and to a certain extent, clouds as well. The majority of the atmosphere exists beneath the tropopause, within the troposphere, and therefore the vast majority of atmospheric heating happens below the tropopause. The radiation which is trapped is the infrared (long wave radiation), and the ultraviolet from the Sun is allowed to pass through the greenhouse gasses (CO2, NO2, etc.).

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