Janice Ramsey, age 11, of Sacramento, Calif., for her question:
What are the three different cloud types?
No one thought of classifying the clouds until about 150 years ago. In 1803 an English weather watcher divided the endless varieties into three main types. He was Luke Howard and he named them cirrus clouds, cumulus clouds and stratus clouds. Howard has improved his classifications but the three basic names remain.
The word cirrus means a curl. The cirrus cloud is that dainty white feather high in the sky. It may be flying six miles above our heads. It is made of tiny fragments of ice and is usually a small cloud.
The word cumulus means a heap. The cumulus cloud is a towering pile of snowy white mist. Usually its base is flaw, and its bulging head is a mass of cauliflowers and pour‑pours. The snowy cumulus sails half a mile to four miles above us.
The word stratus means spread or scattered. The stratus cloud is grey and flat looking. It may be scattered in raged streamers or spread over the sky in a glowering blanket. It may hang a gloomy canopy 300 feet over our heads. The stratus is made of heavy mist waiting for an excuse to rain.
But, as everyone knows, clouds are among the most changeable things in the world. Sooner or later every misty cloud turns into raindrops, hailstones or snowflakes and falls down to earth.
The International Meteorological Committee, that's the world‑wide weathermen, decided to adopt more classes to describe the in‑between stages of the changeable clouds. In 1896 ten cloud types were named and described for weather watchers all over the world.
Some are combinations of the three basic types. Cirrostratus is a pale, whitish veil which gives a milky look to the sky. Cirrocumulus is a flock of filmy white feathers and pour‑pours, too thin and too small to have shadows. Stratocumulus is a patchy layer of dark grey and pearly cloudlets. This cloud formation sometimes covers the sky with waves and rope‑like roll.
The word nimbus is added to describe the clouds heavy with rain. The word alto is added to describe high‑flying clouds. Altocumulus is a patch of small, white clouds, some call it a mackerel sky. Altostratus is a heavy veil of grey or bluish‑grey. It is thick enough to hide the sun and is full of the promise of rain.
Nimbostratus keeps its promise of rain for sure. It smothers the sky in a dense, dark layer of cloud and can bring rain or snow for several days on end. Cumulonimbus is the most dramatic of all the cloud forms. This is the fair weather cumulus that turns into a storm cloud and is, of course, the thunderhead.
The beautiful clouds have beautiful names, what’s more, you only need learn five small words to know them all. The cirrus cloud is a curl, the cumulus cloud is a pile and the stratus cloud spreads over the sky. Mix up the threw basic names and add alto for the high‑flying clouds and nimbus for the rain clouds. Soon you will be able to recognize and name the ten different varieties.