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Arizona State University
Chain Reaction
STORIES OF SCIENCE AND LEARNING FROM ARIZONA STATE UNIVERSITY
Weather | Desert | Solar System | Urban Ecology Weather StationMeet Clouds by Nameby Conrad J. Storad Clouds can make us happy. Clouds can make us sad. Big puffy white clouds floating through a bright blue summer sky make us smile. But boiling black storm clouds slashed with jagged lightening and crashing thunder make us run for shelter. To be precise, a cloud is nothing more than a collection of water particles or ice crystals floating in the atmosphere. There are 10 different types of clouds. In 1803, English pharmacist Luke Howard identified these distinct cloud types. He then devised a system of cloud classification. Howard's cloud classification system uses Latin words that describe the placement and appearance of clouds. For example, using Howard's system, a high (alto), spread out (stratus) cloud is called an altostratus cloud. Meteorologists still use Howard's system today because it is so simple and effective. Five of the 10 types of clouds can be found at low altitudes. The low-altitude clouds are called stratus, cumulonimbus, cumulus, nimbostratus, and stratocumulus. Stratus clouds are spread out, dull clouds usually found at ground level. Stratus clouds are so close to the ground they are identified as fog. Cumulonimbus clouds are piled up high like scoops of dark ice cream. These clouds usually bring rain showers. Cumulus clouds look like giant heads of cauliflower because they are white and fluffy. Dark, flat nimbostratus clouds often produce rain or snow. Stratocumulus clouds are spread out heaps of dense cover that rise higher in the atmosphere. Altocumulus and altostratus are middle-altitude clouds. Even though the word alto means "height" in Latin, these are not the highest clouds. Altocumulus clouds look fleecy and have dark, shadowed sides. Altostratus clouds are flat and make the sun look as if it is being seen through a misty glass. Clouds forming in high altitudes are called cirrus, cirrostratus, and cirrocumulus. It is so cold in the upper atmosphere that high altitude clouds contain ice crystals instead of water particles. Cirrocumulus clouds look like upside down waves rolling across the sky. High, thin cirrostratus clouds look much like stratus clouds, but cirrostratus clouds contain ice crystals and are much higher. Cirrus clouds form when the wind blows these ice crystals into wispy streaks that look like thin horse tails.
Can you match clouds with their names? How do clouds form? "I know that clouds are formed by molecules of water all smooshed together. But how can they be in different shapes?" |