Question

What is true about the thickness of the ozone layer?

It has gradually decreased in the last couple of years.
It has remained the same in the last couple of years.
It has entirely disappeared in the last couple of years.
It has gradually increased in the last couple of years.

Answer 1

Answer: The answer is A (It has gradually decreased in the last couple of years)

• Over the Earth's surface, the ozone layer's average thickness is about 300 Dobson Units, or a layer that is 3 millimeters thick.

• The thickness of the ozone layer changes due to increasing concentrations of ozone-depleting substances in the atmosphere.
• Air motions also increase the ver- tical thickness of the ozone layer near the poles, which increases the value of total ozone in those regions. Tropospheric weather systems can temporarily reduce the thickness of the stratospheric ozone layer in a region, low- ering total ozone at the same time.

• It is thinning due to the release of man-made compounds called chlorofluorocarbons (CFC). The net effect that CFCs have on the ozone layer is to recombine an oxygen atom with an ozone molecule to form two oxygen molecules. From 1978 to 1991, global stratospheric ozone levels have decreased by 3%.

Answer 2

A

Step-by-step explanation:

The top answer is correct, over time it has become weaker.