The reason that ozone is good for you in the stratosphere and not good on the surface of the earth is a matter of what it does. The ozone layer protects the earth by reflec ting harmful radiation back into space. However, the chemicals in ozone, for example in the form of acid rain, can be very destructive to the environment and man-made objects. Clouds can last anywhere from a few minutes to days. The lifespan of a cloud depends upon its type.
Cumulonimus clouds can last for a few minutes, or, in the case of huge storms, twelve hours or more.
Small cumulus clouds last around 10 to 15 minut es. There is not an exact starting place for where the Earth's atmosphere ends and space begins. The Earth's atmosphere just gets less and less as you travel higher and higher. The Earth's atmosphere is kept in place because of the gravitational pull the Earth exerts on particles in the atmosphere. But part of the Earth's atmosphere does float out into space.