Unit 11 Clouds Clouds three main cloud types

Unit #11 Clouds

Clouds • three main cloud types: cirrus, cumulus, and stratus • classified based on shape and altitude • Clouds form when air rises, cools to its dew point, and becomes saturated (basically condensation) • In order to form a cloud, the water vapor must have something to stick to • If the temperature is cold enough, the cloud will be made of ice crystals. If not cold enough, water droplets make up the cloud

LOW CLOUDS • LOW GROUP: 2, 000 meters or less • Cumulus- puffy clouds with flat bottom formed when air currents rise, carrying moisture with them. Stratus- form dull, gray sheets that can cover the entire sky with layers of cloud • Nimbostratus-- low, dark, thick layers that block out the sun •

MIDDLE CLOUDS • MIDDLE GROUP: 2, 000 – 8, 000 meters • Altocumulus- layered and wispy, can produce light precipitation • Altostratus- layered and puffy, can produce light precipitation

HIGH CLOUDS • HIGH GROUP: 8, 000 meters or more • • Cirrus- wispy, feathery high level clouds • made of ice crystals • fair weather Cirrostratus- high, layered clouds that sometimes cover the sky

VERTICAL CLOUDS • VERTICAL GROUP: spans through several different group layers • Cumulonimbus- create the heaviest precipitation of all; known as thunderstorm clouds • TIP: Nimbus= cloud forms precipitation/rain

Precipitation • precipitation-any form of water falls from clouds and reaches Earth’s surface • become too large to be suspended by clouds • Forms include: • Rain • Freezing rain • Hail • Sleet • Snow

Precipitation • Rain Gauge- open-ended tube that collects and measures rain

Precipitation Freezing rain- rain falls as liquid water and hits a cold surface Snow- water vapor in a cloud converts to ice crystals and join together

Precipitation Hail- round pellet of ice carried through updrafts multiple times and new layers form Sleet- rain falling through air below freezing as solid particles of ice

Wind • difference in air pressure causes air to move • Air moves from high air pressure areas to low pressure areas • Wind- movement of air parallel to Earth’s surface • REMEMBER Low pressure = warm air rises • High pressure = cold air sinks • The greater the difference in temperature or pressure between two areas, the stronger the winds will blow between them •

Wind local winds- winds that blow over short distances unequal heating of Earth’s surface in a small area causes local winds • 2 types of local winds: sea breeze and land breeze • sea breeze- during the day, local wind that blows in from an ocean • • cool air blows in from ocean and moves under warm air on land • land cools off faster than water so cool air from land moves under warm air on water land breeze- at night, local wind flows from land to ocean

Weather Instruments Anemometer to measure wind Hygrometer to measure humidity Thermometer to measure temperature Barometer to measure atmospheric pressure

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