Consider the following statements relating zones of atmosphere to altitude: 1. Temperature decreases with altitude in troposphere. 2. Speed of sound decreases with altitude in troposphere. 3. Temperature increases with altitude in stratosphere. 4. Ozone is present in stratosphere which protects people from harmful effects of solar radiation. Which of the above statements are correct?

Layer of Atmosphere

Characteristics

Troposphere

1. All weather phenomena like clouds, Rain, snow etc occurred here, due to which aircrafts does not fly in this region.

2. Temperature decreases with increase in Height, by about 6.5°C per kilometre.

3. Pressure also decreases with increase in height.

4. Speed of sound is directly proportional to temperature, which means that it decreases with increase in height.

Stratosphere

1. Temperature increases with increase in height.

2. Ozone layer is present which absorbs the harmful UV rays from sun.

Mesosphere

1. The temperature again decreases with height, reaching a minimum of about -90°C.

Thermosphere

1. Temperature increases with height.

2. A thin layer called ionosphere is present in which energetic solar radiation knock out electrons off molecules and atoms, turning them into "ions" with a positive charge.

Exosphere

1. Outermost layer of atmosphere.

2. It contains mainly oxygen and Hydrogen which are separated by very large distance and due to which they never collide with each other.