Consider the following statements:
- 1. The troposphere contains almost all weather phenomena.
- 2. The stratosphere is mostly free of clouds and has the ozone layer.
- 3. The mesosphere protects the Earth by burning up meteoroids.
Which statement(s) is/are correct?
- A1 and 2 only
- B2 only
- C1 and 3 only
- D1, 2 and 3
Show answer and explanation
Correct answer: (d) 1, 2 and 3
Explanation
All three statements are correct.
- 1. The troposphere, the lowest layer, contains almost all the water vapour and dust, so nearly all weather (clouds, rain, storms) happens here. Its height is about 8 km at the poles and 18 km at the equator.
- 2. The stratosphere above it is calm and mostly free of clouds, which is why jet aircraft fly in its lower part. It contains the ozone layer, which absorbs the Sun's harmful ultraviolet rays.
- 3. In the mesosphere, most meteoroids burn up through friction with the air, seen as shooting stars. It is the coldest layer of the atmosphere.