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Weather Factors. Chapter Two. Energy in the Atmosphere. Most energy from the sun reaches Earth in the form of visible light and infrared radiation, and a small amount of ultraviolet radiation.
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Weather Factors Chapter Two
Energy in the Atmosphere • Most energy from the sun reaches Earth in the form of visible light and infrared radiation, and a small amount of ultraviolet radiation. • When Earth’s surface is heated, it radiates some of the energy back into the atmosphere as infrared radiation.
Key Terms: • Electromagnetic waves: A form of energy that can travel through space. • Radiation: The direct transfer of energy by electromagnetic waves. • Infrared radiation: A form of energy with wavelengths that are longer than visible light. • Ultraviolet radiation: A form of energy with wavelengths that are shorter than visible light. • Scattering: Reflections of light in all directions • Greenhouse Effect: The process by which heat is trapped in the atmosphere by wayer vapor, carbon dioxide, methane, and other gases that form a “blanket” around Earth.
Heat Transfer • The energy of motion in the molecules of a substance is called thermal energy. • Three forms of heat transfer work together to heat the troposphere. They are: Radiation Conduction Convection
Key Terms • Thermal energy: The energy of motion in the molecules of a substance. • Temperature: The average amount of energy of motion in the molecules of a substance. • Thermometer: An instrument used to measure temperature consisting of a thin, glass tube with a bulb on one end that contains a liquid (usually) mercury or alcohol. • Heat: The energy transferred from a hotter object to a cooler one. • Conduction: The direct transfer of heat from one substance to another substance that is touching. • Convection: The transfer of heat by the movement of a fluid.
Winds • All winds are caused by differences in air pressure. • Local winds are caused by unequal heating of Earth’s surface within a small area. • The movement of air between the equator and the poles produces global winds. • The major global wind belts are the trade winds, the prevailing westerlies and the polar easterlies.
Key Terms • Wind: The horizontal movement of air from an area of high pressure to an area of lower pressure. • Anemometer: An instrument used to measure wind speed. • Wind-chill factor: Increased cooling caused by the wind. • Local wind: Winds that blow over short distances. • Global wind: Winds that blow steadily from specific directions over long distances. • Sea Breeze: The flow of air from an ocean or lake to the land. • Land breeze: The flow of air from land to a body of water. • Coriolis effect: The way Earth’s rotation makes winds in the Northern Hemisphere curve to the right and winds in the Southern Hemisphere curve to the left. • Latitude: The distance from the equator, measured in degrees.
Water in the Atmosphere • Clouds of all kinds form when water in the air becomes liquid water or ice crystals.
Types of Clouds • Meteorologists classify clouds into three main types: Cumulus Stratus Cirrus
Key Terms • Evaporation: The process in which water molecules iin liquid water escape into the air as water vapor. • Humidity: A measure of the amount of water vapor in the air. • Relative humidity: The percentage of water vapor in the air compared to the maximum amount the air cloud hold at that temperature. • Psychrometer: An instrument used to measure relative humidity, consisting of a wet-bulb thermometer and a dry-bulb thermometer. • Condensation: The process by which molecules of water vapoar in the air become liquid water. • Dew Point: The temperature in which condensation begins. • Cumulus: Clouds that form least than 2 kilometers above the ground and look like fluffy, rounded piles of cotton. • Stratus: Clouds that form in layers. • Cirrus: Wispy, feathery clouds made mostly of ice crystals that form at high levels, above about 6 kilometers.
Precipitation • Rain, sleet, freezing rain, hail and snow • Rain is measured with a rain gauge • Scientists have used cloud seeding to produce rain and to clear fog from airports
Key Terms • Precipitation: Any form of water that falls from clouds and reaches Earth’s surface. • Rain Gauge: An instrument used to measure the amount of precipitation, consisting of an open-ended can topped by a collecting funnel and having a collecting tube and measuring scale inside. • Drought: Long periods of low precipitation.