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Weather and Climate Definitions • Meteorology- is the study of the atmosphere- including weather. Weather-the daily conditions of the atmosphere. It can change from time to time and place to place. Climate- the type of weather an area has over a long period of time. Layers of the atmosphere • Layers of the atmosphere: separated by difference of temperature patterns. Troposphere Gases present In Troposphere We live in the troposphere. • 0-12 km • Temperature decreases • All weather occurs here • All water vapor in the atmosphere is here • Contains people, clouds, airplanes Other layers Stratosphere • Temperatures increase • Home of the Ozone layer. • 12-50km • Mesosphere • Upper layers- temperatures get colder (coldest layer) • The air is very thin here. • Where meteors will burn up Thermosphere • 82-600km • Gets very hot as you go up • Contains aurora borealis • Sub layers: ionosphere, and exosphere Northern Lights • Aurora borealis happens in ionosphere. Aurora Borealis is also called the Northern Lights. They happen when sun rays enter ionosphere and hit the moving molecules. This is sometimes called magnetic storm. What we see is a glow in many colors. Things that change in atmosphere • Temperature • Water content and humidity • Air pressure • Cloud Cover • Wind Speed • Precipitation Temperature • Measures the average kinetic energy (energy of motion) of molecules. • Heat enters atmosphere from the sun as incoming solar radiationinsolation 3 ways to measure Temp. • Fahrenheit – Water freezes at 32° – Water boils at 212 ° • Celsius – Water freezes at 0 ° – Water boils at 100 ° • Kelvin – Water freezes at 273K – Water boils at 373K Temperature Conversions Isotherm- line connecting locations of equal temperature Air Pressure • Caused by weight of the air • Weight of the air above earth’s surface pushes down on the surface so there is pressure exerted on the surface Air pressure • Air pressure is greatest • Why are we not closer to the surface of crushed by air the earth pressure? • Average pressure is 14 pounds (lbs.) per square inch • Ans: air pressure is pushing out at the same time it is pushing in Factors affecting air pressure: • 1. Elevation(altitude)- the higher the elevation the lower the air pressure (air is thinner- less weight is pushing down) • 2. Temperature- warmer the air, lower the pressure • 3. Moisture/Humidity- more water vapor that goes into the air, the lower the air pressure Measuring air pressure • Barometer- an instrument used to measure changes in air pressure 1. Mercury barometer Measuring air pressure • 2. Aneroid barometer • Measured in millibars= average 1013mb • Range- 970- 1040mb Moves clockwise and outward Moves counterclockwise And inward Pressure Conversions HIGH 1013.2 LOW Isobars- lines connecting patterns of equal air pressure Example: Isotherms v. Isobars • Isotherms (Temp) – Generally DOES NOT end in circles. – ALWAYS goes from one side of the U.S. to the other • Isobars (Pressure) – Can be lines or circles-can end in the middle of the map – Intervals of 4 – Would have a H or L inside the center IN BOTH, YOU CANNOT CROSS LINES!!!! Winds move from high to low pressure Wind- the movement of air parallel to the ground • Caused by differences in air pressure and temperature • Closer the isobar lines, faster the wind speed Draw the lines around a High and a Low H L Wind direction • Winds are named for the direction that they come from • On a map direction is shown with a line showing where it came from. Sea Breeze- Day • Water has a high Air sinks over water and moves to land specific heat= takes longer to warm up and cool down • Air over water is cooler, so it sinks and a breeze moves from water to land Land Breeze- Night • At night , the land will cool down faster than the water- the breeze then moves from land to sea Relative Humidity • The amount of water in the air is called humidity. • The ability of air to hold water changes depending on the temperature. • Relative humidity tells "how full" the air is with water. • It is expressed in %. • 100% is full and can't hold any more. • Water gets into the air by evaporation(liquid to gas) Dew Point • To get the water out of the air it either condenses or sublimes. • condense-changing from gas to liquid.- dew • Dew Point- the temperature at which condensation begins • Frost – dew that freezes due to the temperature dropping below the dew point. At this point- condensation can begin and clouds will start forming Measuring Relative Humidity & Dew Point • The “Dry Bulb” - It is just a thermometer. – It measures the air temperature. • The “Wet Bulb” – Has a little wet booty tied to the bottom. – Gets cool when water evaporates. Wind speed- measured in knots Converting air pressure • Converting from millibars to station model code – use only the last three digits and throw out the decimal point – Example: 1020.5 = 205 • Converting from station model to millibars – if the code is 500 or higher put a 9 in front, otherwise put a 10 – Example: 281= 1028.1 Try these: (>500 put 9 in front) (<500 put 10 in front) • 1008.4= 084 • 987= 998.7 • 976.6= 766 • 888= 988.8 • 1022.2= 222 • 168= 1016.8 • 992.2= 922 • 080= 1008.0 Clouds- how they form • Form by process called condensation – This happens when the air is so moist that it can no longer hold any water. – = air is saturated • In order for anything to happen: – the sun must heat the earth which heats the air above it and rises into the atmosphere. • As air rises, it cools because of expansion and moving away from heat source • Air will then cool enough to reach dewpoint • Water vapor then condenses into condensation nuclei • When enough droplets condense- we see them as clouds Why clouds look different • Clouds are usually a mixture of both water vapor droplets and ice crystals. The water and ice scatter all light, making clouds appear white. If the clouds get thick enough or high enough all the light above does not make it through, hence the gray or dark look. Also, if there are lots of other clouds around, their shadow can add to the gray or multicolored gray appearance. When air is forced to rise because it hits mountains, it will cool and condense - Windward side of the mountains will have a cool, moist climate. - Leeward side- there will be a warm, dry climate Windward Leeward When air is forced to rise because it hits mountains, it will cool and condense On the Leeward side, there will be a dry climate that is usually warmer than the windward On the Windward side of the mountains it will have a moist climate.