Clouds move because they are carried by wind. The speed, direction and strength of wind all influence cloud movement. Heavy clouds can remain still even with strong wind.
The speed of wind increases with altitude and decreases closer to the ground. All levels of the atmosphere have wind. Clouds occurring at an altitude of approximately 30,000 feet move very quickly because of the high speed of wind at this level. Fast-moving winds at high altitudes are called jet streams. This wind causes clouds to move up to 175 mph. Clouds normally appear white because of shining sunlight. Thick clouds obscure sunlight, causing them to appear gray or dark.
Cloud movement also influences the weather of a specific location. Clouds are made of tiny water droplets and fall to the ground in the form of snow or rain. Clouds form due to water evaporation from water masses, such as lakes, oceans, ponds and rivers. Clouds move to higher altitudes due to pressure differences. Clouds at varying altitudes can move in different directions, and they have different cooling and warming effects. Cloud movement and appearance are used to predict global warming, or climate change. Meteorologists use satellites to track cloud movement in order to forecast the weather.