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Understanding Weather

Science, Grade 7

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H L L L evaporation condensation ocean river discharge precipitation precipitation water storage in snow evapotranspiration ru no ff in filt ra tio n water table ground water discharge Stratus (spread out or layered) Cirrus (curly, wispy) Cumulus (heaped or piled up) Photos courtesy of NASA and NOAA. What Is Weather? The condition of the atmosphere at a specific time in a specific place is known as weather. The weather includes and is affected by water, wind, temperature and air pressure. Meteorologists are scientists who study and predict weather and weather patterns. Humidity and Precipitation As water evaporates from oceans, lakes and rivers, it is held in the air. The amount of water vapor in the air is called humidity. Relative humidity is a percentage that compares the amount of water vapor in the air with the maximum amount of water vapor the air can hold at a specific temperature. Precipitation is water that has condensed in the atmosphere and falls to Earth. Sleet, snow, rain and hail are different forms of precipitation. The type that falls at a given time depends on the temperature. Amount of Water Vapor Air Can Hold at Various Temperatures Temperature (ºC) W ater v a por ( g/m 3 ) 0 -10 0 10 20 30 40 50 10 20 30 40 50 20 30 40 50 60 70 80 90 10 0 HUMIDITY The Sun’s Energy & the Water Cycle The continuous movement of water from the Earth’s surface to the atmosphere and back is called the water cycle. Energy from the Sun heats water causing it to evaporate. Plants and animals also give off water; this is called transpiration. The largest source of atmospheric water vapor is the oceans. This water vapor accumulates in the atmosphere and forms clouds under proper conditions. Water eventually precipitates out of the clouds and falls back to Earth either as rain, snow or sleet. Types of Clouds Clouds are categorized based on their form and composition. Cloud Formation Clouds form when minute droplets of water or ice crystals accumulate in the atmosphere. A variety of cloud types form depending upon their height, air movement and the amount of water vapor and condensation particles. Reading Weather Maps A weather map is a collection of weather data in the form of symbols indicating the weather conditions of a large geographic region at a particular time. Sunlight warms the surface and water evaporates. As the air containing this evaporated water rises, it cools. At a certain altitude, condensation begins as the air cools to the dew point. As this cooling occurs, the water vapor condenses (changes) from a vapor to a liquid forming a cloud. 1. 2. 3. Weather Map Symbols warm front cold front stationary front H high pressure L low pressure snow rain thunderstorm Understanding Weather © Copyright NewPath Learning. All Rights Reserved. 94-4109 www.newpathlearning.com

ocean river discharge water storage in snow evapotranspiration ru no ff in filt ra tio n water table ground water discharge H L L L • air pressure • cirrus • cold front • condensation • cumulus • evaporation • high pressure • humidity • low pressure • meteorologist • precipitation Key Vocabulary Terms • relative humidity • stationary front • stratus • temperature • transpiration • warm front • water cycle • weather • weather map • wind \|xiBAHBDy01795qzZ Photos courtesy of NASA and NOAA. What Is Weather? What is weather? ______________________________ ______________________________ ______________________________ Scientists who study weather are called ________________________. Humidity and Precipitation Describe: Humidity: _________________________________________ ___________________________________________________ Relative humidity: __________________________________ ___________________________________________________ Precipitation: ______________________________________ ___________________________________________________ The Sun’s Energy & the Water Cycle The continuous movement of water from the Earth’s surface to the atmosphere and back is called the ________________ _______________. Energy from the Sun heats water causing it to __________________________. Plants and animals also give off water; this is called ___________________________. The largest source of atmospheric water vapor is the oceans. This water vapor accumulates in the atmosphere and forms clouds under proper conditions. Water eventually ____________________________ out of the clouds and falls back to Earth either as rain, snow or sleet. Types of Clouds Clouds are categorized based on their form and composition. Cloud Formation How do clouds form? What is a weather map? _________________________ _____________________________________________ _____________________________________________ 1. _________________________________________ _________________________________________ 2. _________________________________________ _________________________________________ 3. _________________________________________ _________________________________________ Weather Map Symbols warm front cold front stationary front H high pressure L low pressure snow rain thunderstorm Amount of Water Vapor Air Can Hold at Various Temperatures Temperature (ºC) W ater v a por ( g/m 3 ) 0 -10 0 10 20 30 40 50 10 20 30 40 50 Understanding Weather © Copyright NewPath Learning. All Rights Reserved. 94-4109 www.newpathlearning.com

Understanding Weather

Science, Grade 7

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