METEOROLOY STUDY GUIDE ATMOSPHERE 1: Why is the atmosphere important? (3 reasons) contains oxygen, traps heat, protects us from the sun’s ultraviolet radiation 2: What is the composition of the atmosphere? 78 % nitrogen and 21 % oxygen plus water vapor and other gases. 3: What are the characteristics of the 4 main layers of the atmosphere? (starting at Earth and going up) Troposphere, stratosphere, Mesosphere, Thermosphere Tropo- means turning or changing, weather occurs here, closest layer to Earth Strato- means spread out, contains the ozone Meso- means middle, protects earth from being hit by most meteoroids Thermo- means heat, this layer is divided into two layers: top layer - exosphere and bottom – ionosphere 4. What is the relationship between altitude and air pressure? As altitude increases (going up a mountain), air pressure deceases (and density decreases). As altitude decreases, air pressure increases (and density increases). Air pressure – the pressure caused by the weight of a column of air pushing down on an area Altitude - elevation above sea level Barometer – an instrument used to measure changes in air pressure Weather - the condition of Earth’s atmosphere at a particular time and place (changes day to day. ex: rainy on Monday, sunny on Tuesday) ENERGY AND HEAT TRANSFER 5: How is heat transferred? 3 ways: conduction, convection, radiation (cold doesn’t transfer) conduction __B___ A. form of waves, warmth from sun convection __C___ B. when two objects touch, a pot touching a hot stove radiation __A____ C. through liquid or gases, main way atmosphere is heated 6: How does energy from the sun travel to Earth? The sun emits electromagnetic waves that travel through the atmosphere by radiation. Some of the energy is reflected back into the space, some is absorbed by the atmosphere, and some reaches Earth. Heat – the transfer of thermal energy from one object to another because of differences in temperature. Green house gas effect- the process by which heat is trapped in the atmosphere (this keeps us warm) Global warming – a gradual increase in the temperature of Earth’s atmosphere. WIND Wind - the horizontal movement of air from an area of high pressure to an area of low pressure. 7: What causes winds? Unequal heating of Earth’s surface (which will cause differences in density) Warm air rises, cold air moves in underneath. Then the cool air is near the surface of Earth and begins to heats up so it rises and cool air moves in underneath. (creates convection currents) 8: Name and describe the global winds. Global winds blow over long distances. 9: Name and describe the two types of local winds. Local winds blow over short distances. 2 types: Sea Breeze – the flow of cooler air from over an ocean or lake toward land. (will occur during the day, when the land heats up faster) Land Breeze- the flow of air from land to a body of water (will occur at night, when the water is warmer) AIR MASSES & FRONTS Air mass –a huge body of air that has similar temperature, humidity, and air pressure throughout. Front - boundary where two air masses meet but do not mix Humidity - the amount of water vapor in a given volume of air Storm – a violent disturbance in the atmosphere 10: What are the major types of air masses? Maritime Tropical – wet, warm Continental tropical – dry, warm Maritime Polar – wet, cold Continental Polar – dry, cold 11: How do air masses move? In the United States, air masses are moved by the Prevailing Westerlies and jet streams. 12: What are the main types of fronts? HOW IT FORMS Cold air mass pushes under a warm air mass forcing Cold Front warm air to rise Moist, warm air mass slides up and over cold air Warm Front mass Stationary Front Warm and cold air meet and neither air mass can force the other to move Warm air mass gets caught between two cold air Occluded Front masses. The warm air rises and the cold air masses join. WEATHER IT BRINGS Can cause thunderstorms, followed by cool fair weather Can cause gentle rain or snow, followed by warmer weather Can cause days of cloudy, rainy weather Temperature drops, can cause strong winds and heavy rains