HOW ARE CLOUDS FORMED?
Clouds are formed when warm moist air rises into the sky. When it reaches a certain height, the warm air cools down and the water vapor in it condenses into small drops of water, forming clouds.
There are several different types of clouds. The ones which are highest are usually made up of drops of ice and are the thinnest. These are called cirrostratus and cirrocumulus clouds. Lower clouds are called altostratus and altocumulus clouds.
Lower still are the stratocumulus clouds and the nimbostratus clouds- these are the thick and shapeless rain clouds -and the lowest of all are the stratus clouds, which are seen as fog over high, mountain regions. Thunder clouds are called cumulus and cumulonimbus clouds, and these are the fat, cauliflower-shaped ones.
WHEN WILL THE EARTH DIE?
As you have already seen, the very existence of the Earth, and all the other planets in the solar system, depends upon the Sun. You have seen how the Sun provides enormous amounts of energy by the change of the gas hydrogen into the gas helium. But as with any other engine’ the fuel, that is the hydrogen, must slowly be used up. When this happens, as has already occurred with millions of other stars, the Sun will collapse and explode. The explosion will totally destroy the Earth and its neighbors. There is no need to worry unnecessarily – it will be at least another 5000 million years before the Sun explodes.
HOW MANY STARS ARE THERE?
If you look up into a clear night sky in the heart of the country well away from town light, you will be able to see about 2,000 stars. In the entire sky, there are between 5,000 and 6,000 stars visible to the naked eye. But there are millions upon millions of stars to be seen through a powerful telescope.