Norman Horsley, Jr., age 13, of Bel lamy, Va for his question:

What are cumulo nimbus clouds?

Clouds bring rain and for this reason they have been watched and studied since man first became a farmer. For countless ages he knew that drifting white pour pour clouds go with gentle weather; low dark clouds bring rain and tall mountains of pearly grey clouds often pile up into thunderheads 4 But not until 1803 did someone think of classifying the different clouds. This weatherman was Luke Howard) an English school teacher.

Howard named only three cloud types   cirrus clouds, stratus clouds and cumulus clouds. Cirrus is coined from an older word meaning curl. A cirrus cloud is a thin, whispy curl, like delicate white hair high in the sky. Stratus is coined from a word meaning leg er. A stratus cloud is a flat stripe or layer high or low in the sky. Cumulus is coined from an older word meaning heap. A cumulus cloud is a drifting, changing pile of white pour pours which we watch on a summer's day.

Later, the weathermen discovered that clouds are forever changing. Cirrus clouds sink down to become stratus clouds. Cumulus clouds pile up into thunderheads. They noticed that the height of a cloud was an important part of its history. They also noticed that certain clouds could bring rain and others could not. The words alto, meaning high, and nimbus, meaning rain, were added to Howardts original cloud classifications. The three original classifications were also mixed together to show clouds changing from one form to another.

Cirro stratus cloud formation is a hazy white veil over the sky. It does not hide the sun, but gives it a halo. An alto cumulus formation is a flock of small, high flying white clouds often called the mackerel sky.

Strato cumulus is a broken layer of grey clouds showing lines and ropey rolls. Alto stratus clouds form a pearly veil over the sky, somewhat thicker than the cirro stratus.

The nimbus clouds are the rain bearing clouds. A nimbo stratus sky is covered with low dark clouds full of rain or snow. Cumulo nimbus occurs when mountains of fluffy white cumulus clouds pile up into e. pearly grey mountain. The base of this cloud is usually flat; the top, many miles high, becomes a ragged mass of twirling grey streamers: This cloud is a wild one and soon spreads itself all over the summer sky.

In a short while, the warm blue sky is hidden and warfare breaks out in the darkening cloud above our heads. We hear the peal of thunder and see the flash of lightning Yes, that's right. Cumulo nimbus is the weatherman's name for a thunderhead.