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Which of the following statements concerning the tropopause is correct?
  • A

    The temperature lapse rate and pressure lapse rate both change abruptly at the tropopause.

  • B
    The temperature lapse rate changes abruptly at the tropopause.
  • C
    The temperature remains constant above and below the tropopause.
  • D
    The temperature of the tropopause at the equator and at the poles is equal.

Refer to figure.

TROPOPAUSE

The tropopause is the upper limit of the troposphere and, therefore, constitutes the boundary between it and the Stratosphere and it is where the temperature remains almost constant with further increase in height (temperature ceases to fall with increasing height). To put this into prespective, when we reach the tropopause, the temperature lapse rate changes from 2ºC/1 000 ft to less than two-thirds of 1ºC/1 000 ft. This is what they mean by "abrupt change".

  • As you can see in the attached figure, in the troposphere, the temperature first decreases with altitude. In the stratosphere, the temperature increases with altitude. This is because the direct heat source for the stratosphere is the sun. Because the stratosphere contains ozone molecules, and these absorbs solar radiation, the temperature increases with altitude in the stratosphere.
    That is why the temperature laps rate changes abruptly at the tropopause.

Recent feedback added the option “temperature and pressure lapse rate change abruptly at the tropopause”, and we think the feedback indicated it as incorrect, as well as the fact that the temperature lapse rate is the major change (and the only one on the syllabus), and the pressure lapse rate is more complex and unlikely to change suddenly due to the beginning of this isothermal layer.

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