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1. Heat Energy 2. Air Pressure 3. Winds 4. Moisture ENERGY IN THE ATMOSPHERE • Most energy in the atmosphere comes from the sun. • Electromagnetic Waves- sun’s energy that travels to earth. • Classified by wavelength (distance between waves). ENERGY WE RECEIVE FROM THE SUN • Most of the sun’s energy travels to earth in the form of 1. visible light 2. infrared radiation 3. ultraviolet radiation. VISIBLE LIGHT • Includes all colors of rainbow • Different colors = different wavelengths • Red/Orange = longest wavelengths • Blue/Violet = shortest NON-VISIBLE RADIATION 1. INFRARED- long waves, not visible but can be felt as heat. 2. ULTRAVIOLET (UV)shorter waves, can cause sunburns. Energy in the Atmosphere 1. Sun’s energy travels in the form of waves. 2. Some sunlight is absorbed by the atmosphere before it reaches the surface. Ozone layer & water vapor absorbs sun’s energy. 3. Most of the sun’s energy is absorbed by land/water & changes into heat. 4. The earth’s heated surface then radiates most of the energy back into the atmosphere as infrared radiation. 4b. Some of the infrared rays get absorbed by water vapor, carbon dioxide, & other gases. • This heats up the air & forms a heat “blanket” around earth. •Carbon dioxide & other gases act like a blanket trapping heat in the air. •Infrared rays can’t escape into the atmosphere thus keeping the heat on earth. Scattering- reflecting light in all directions. Gas particles scatter short wavelengths (blue/violet) more. SCATTERING EFFECTS Scattered light looks bluer than ordinary light which is why the sky looks blue. • Sunrise/Sunset- light passes through a greater thickness at this time so more orange/red light gets through. Sec. 2 HEAT TRANSFER TEMPERATURE • The average amount of energy/motion of a particular substance. • A measure of HOT/Cold. • Particles are constantly moving, the faster the particles are moving– the more energy they have. THERMAL ENERGY • Total energy motion in the particles of a substance. • Iced Tea has less thermal energy than Hot Tea. Thermometer •Measures air temp. •The liquid will expand if its hot or contract if it is cold. TEMP. IS MEASURED IN • CELSIUS SCALE (scientists) • 0C water freezes, 100C boiling point of water. • FAHRENHEIT SCALE (US) 32F water freezes, 212F boils 3 WAYS HEAT IS TRANSFERRED 1.Conduction 2.Convection 3.Radiation • Direct transfer of heat energy from 1 substance to another. • Hand touching a hot stove • Earth absorbs sun’s energy & the surface becomes warm. • transfer of heat energy in a fluid (gas/liquid). • Air near earth’s surface is heated, it becomes less dense & rises. Cooler air sinks. • Most of the heat energy in the atmosphere is transferred this way. • Transfer of heat energy through space in the form of waves. • Heat from the sun reaches earth by radiation How the Troposphere is Heated 1. Sunlight enters as radiation. 2. As earth warms, heat is absorbed by the surface (conduction). 3. Heat from the surface rises into the atmosphere (convection). Heat is transferred through the troposphere by convection. WIND •Caused by the unequal heating of the earth by the sun. •Horizontal movement of air from an area of High Pressure to an area of Low Pressure. WIND MOVEMENT • When air is heated, atoms expand & is less dense, rises = Area of Low Pressure • When air cools, particles slow down/come together & is more dense, sinks = Area of High Pressure. Cooler (denser) air moves in underneath warmer (less dense) air. MEASURING WIND Wind vane- measures wind direction, the name of the wind tells where the wind started. South Wind blows from the south towards the north. • Anemometer- uses a set of cups that spin on an axel. Wind turns the cups & a meter measures the speed. (MPH or Knots.) WIND-CHILL FACTOR • A measure of how cold you feel when outside in cold temps. • Wind blowing over skin removes heat from your body. (stronger the wind, the colder you feel) ANGLE OF SUN’S RAYS •Most direct sunlight occurs at equator. The farther away from equator, the less radiant energy you receive. •Equator- hot, Poles- cold 2 TYPES OF WINDS 1.Global Winds- blow from specific directions, cover long distances 2.Local Winds- blow from any direction, cover short distances Types of Local Winds Seabreeze- flow of air from sea to land. Cool air from sea takes rising warm air’s place land. 2. Landbreeze- flow of air from land to sea. At night, Land cools off faster than water, cooler land air replaces warm rising air from the sea. •Warm air at equator rises & moves toward the poles. At poles, cooler air sinks & moves toward equator. GLOBAL WIND BELTS •Apparent shift in the path of the wind due to rotation of the earth. •e curve to left. CORIOLIS EFFECT • All winds in the Northern Hemisphere curve to the right as they move towards the equator. Winds in Southern Hemisphere curve to left. 1.DOLDRUMS- at equator, very little wind, air is warmed rapidly creating an area of Low Pressure. 2. TRADE WINDS- 30N/S of equator, warm air starts to cool & sink creating wind, High Pressure. 3. PREVAILING WESTERLIES- strong winds 60N & S latitude, plays a role in weather of United States. 4. POLAR EASTERLIES- cold, weak winds. Causes many changes in weather in US. Bands of High Speed winds about 10km above Earth’s surface. Usually blow west to east at speeds of 200 to 400kmph. Pilots can save time/gas • The movement of water between the atmosphere & the earth’s surface. • Process by which water molecules escape into the air. • Moisture enters into the air. • Sun’s energy turns liquid water into a gas or water vapor. Winds carry it all over the earth. •Water vapor or moisture in the air •Varies from place to place •Percentage (%) of moisture the air holds relative to the amount it can hold at a given temp. Example • At 80F, 1kg of air can hold 12g of moisture. It’s only holding 9g now so the relative humidity 9/12 X 100 = 75% PSYCHROMETER •Instrument that measures relative humidity •2 thermometers used: dry, wet one • When air passes over the wet bulb, water in the cloth evaporates & cools the wet bulb temp. Low Humidity = evaporation goes quickly, temp drops quickly High Humidity = evaporation goes slowly, temp hardly changes. Reading the Chart • Subtract the two temps • Take that number & look for it on the chart & match it with the dry bulb temp. to get the humidity. Holding Moisture • Warm air holds more moisture at earth’s surface than cold air. • As the warm air rises, it can no longer hold as much moisture so it condenses & changes to a liquid (rain). DEW POINT • The temp. at which water vapor condenses. • Condensation- process where water vapor becomes liquid water. CLOUD FORMATION • Formed when moisture in air condenses • A mixture of liquid (water) suspended in a gas (air). DEW • Formed when the ground reaches the temp. at which water vapor condenses. • Dew Pt. Above freezing = water vapor forms water droplets • Dew Pt. Below freezing = frost 2 FACTORS FOR CONDENSATION 1. The cooling of air to the dew point or below. 2. The presence of particles (salt, dust from soil, & smoke) 1. Cumulus 2. Stratus 3. Cirrus CIRRUS CLOUDS •Feathery with tails •Indicates rain or snow will fall soon CUMULUS CLOUDS Fluffy, white cotton balls •Indicates fair weather, large & dark, thunderstorms are likely (cumulonimbus clouds) •Nimbus = rain •Alto = high STRATUS CLOUDS • Smooth, gray clouds that cover the whole sky & block out the sun. • Rain or drizzle, FOG Precipitation *Any form of water that falls from the clouds & reaches earth’s surface. *Rain, sleet, snow, hail TYPES OF PRECIPITATION 1. Rain- most common, drops of water less than .5 mm. Smaller drops- drizzle then mist. 2. Sleet- raindrops that freeze into solid particles of ice. 3. Freezing Rain- rain that freezes once it hits a cold surface. Doesn’t freeze in the air. 4. Snow- water vapor in a cloud is converted to ice crystals (snowflakes). 5. Hail- round pellets of ice larger than 5mm. Ice pellets are tossed in clouds, gain layers of ice, & turn into hail. DROUGHT •Long periods of unusually low precipitation •Drier than usual RAIN GAUGE •A container that collects and measures rainfall. •Measured in mm, cm, SNOWFALL MEASURING • Usually measured with a measuring stick or by melting collected snow & measuring the water depth. • 10cm of snow = 1 cm of rain