A) how thick is earth’s atmosphere? name one characteristic of the troposphere and one characteristic of the stratosphere.
b) where is the "ozone layer" located?
c) describe how and why stratospheric ozone is beneficial for people, whereas tropospheric ozone is harmful.
d) describe a temperatures inversion. explain how inversions contribute to severe smog episodes such as the ones in london, england, and in donora, pennsylvania.

Ai) The Earth's atmosphere is estimated to be about 300 miles (i.e. 480 kilometers) thick, although most of the atmosphere is within 10 miles (16 km) the surface.

Aii) The troposphere is characterized by intense mixing due to both horizontal and vertical interactions, it consist of most of the dust and vapour. The stratosphere is quite dry and possess very little vapour.

Bi) The ozone layer is mainly found in the lower parts of the stratosphere, from about 15 - 35 kilometers from the Earth's surface (9.3 - 21.7 miles).

C) ozone is naturally located mostly in the lower parts of the stratosphere. ozone in the stratosphere is beneficial for human survival because it blocks ultra violet radiation, but when it is present in the troposphere, it acts as green house games which is harmful to humans .

D) Temperature inversion is a condition in which the temperature of the atmosphere increases with altitude increase instead of the normal decrease of temperature with altitude.

When an inversion occurs, warmer air is held above cooler air; the normal temperature profile with altitude is reversed. An inversion can lead to air pollution being trapped causing a smog, close to the ground.