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EARTH'S ATOMOSPHERE
Earth is protected by a blanket of AIR (GASES) called the ATMOSPHERE. The Earth's Atmosphere is a mixture of GASES, SOLIDS, AND LIQUIDS THAT SURROUNDS THE PLANET.
COMPOSITION OF THE ATMOSPHERE:
1. DRY AIR is 78% NITROGEN, 21% OXYGEN, and one percent other gases, which include CARBON DIOXIDE AND ARGON. The amount of WATER VAPOR in air varies from ZERO TO FOUR PERCENT. DUST, SMOKE, AND WASTE GASES (POLLUTANTS) from industry and transportation are also in the Air.
2. NITROGEN COMPOUDS are plant nutrients. Few Plants can take nitrogen directly from the air. Bacteria in the Soil change Nitrogen in the Atmosphere to a form that can be used by plants.
3. Animals (including US) eat plants and return nitrogen back to the soil in their body waste.
4. Nitrogen also is return to the soil as plants decay.
5. THIS PROCESS OF USING AND RETURNIG BACK TO THE EARTH IS CALLED THE NITROGEN CYCLE.
6. OXYGEN IS NEEDED BY MOST LIFE FORMS. Animals (including US) use this gas directly from the AIR or Dissolved in Water. GREEN PLANTS during PHOTOSYNTHESIS MAKE oxygen. (LIGHT ENERGY + CARBON DIOXIDE + WATER = SUGAR)
7. CARBON DIOXIDE make up a SMALL Percentage of the air, but is an important gas. Without Carbon Dioxide, Plants could not produce OXYGEN.
8. The amount of WATER VAPOR in the air varies from place to place and from time to time.
9. WATER AND CARBON DIOXIDE ARE BOTH ESSENTIAL FOR LIFE PROCESSES.
10. Water Vapor, like carbon dioxide, helps prevent heat loss from earth.
11. Another important gas, OZONE is a form of OXYGEN that absorbs most of the ULTRAVILOET RADIATION that enters the Earth's Atmosphere. Ultraviolet Radiation can cause skin cancer, genetic mutations, and cataracts. Jet emissions, fallout from nuclear explosions, some fertilizers, and FLOROCARBONS can Destroy Ozone Molecules.
12. Loosing our Ozone will cause more Ultraviolet Radiation to reach the Earth's Surface. FLOROCARBONS that were once used in Refrigerants and in Propellants for aerosol sprays were destroying the Ozone Level of our Atmosphere. Most countries have banned the use of these products, but scientists believe much damage has been done to the Atmosphere. The damage is refereed to as the Ozone Hole.

STRUCTURE OF THE ATMOSPHERE
1. The Atmosphere is divided into FOUR LAYERS based on TEMPERATURE.
1. TROPOSPHERE
2. STRATOSPHERE
3. MESOSPHERE
4. THERMOSHERE
2. The TROPOSPHERE is the layer NEAREST Earth. It contains 75% of the gases of the atmosphere, as well as DUST, and WATER VAPOR. This Layer is the ZONE where WEATHER and CLOUDS occur. Temperature DECREASES with INCREASING HEIGHT in the Troposphere. Near the TOP of this layer, between 8 and 20 Km from Earth, a boundary called the TROPOPAUSE act like a CEILING to the Weather Zone. Just below the Tropopause are STRONG WINDS called the JET STREAMS.
3. Above the Troposphere lies the STRATOSPHERE, which extends upward to about 50 Km from Earth. In the LOWER part of the Zone, Temperatures are CONSTANT -50 degrees C. At about 50 Km, Temperatures rise to 0 degrees C. THE STATOSPHERE CONTAINES THE OZONE LAYERS.
4. The MESOSPHERE extends upward from about 50 Km to between 80 and 85 Km. This Layer is the COLDEST ZONE of the Atmosphere. Temperatures decrease to near -100 degrees C at the TOP of the MESOSPHERE.
5. The THEREMOSPHERE extends from about 80 Km upward into SPACE. Temperatures in the Thermosphere increase QUICKLY because of absorption of ENERGY from the SUN.
6. The THERMOSPHERE is Divided into TWO parts; THE IONOSPHERE AND EXOSPHERE.
a. The IONOSPHERE is a layer of Electrical Charged Particles that begins between 80 and 85 Km above the Earth's Surface. Here, particles of the atmosphere are bombarded by Energy from SPACE and form IONS and FREE ELECTRONS. These charged particles are useful for COMMUNICATION because at night they reflect RADIO WAVES. During the Day, radio reception is terrible over long distances because the waves are absorbed. When streams of particles from SOLAR FLARES come in contact with the IONOSPHERE, the IONS glow Different COLORS. THE RESULT DISPLAY IS AN AURORA. Auroras are brightest near the POLES due to the DEFLECTION of the particles by the Earth's MAGNETIC FIELD. PARTICLES FROM SOLAR FLLARES DISTURB RADIO, TV, AND TELEPHONE TRANSMISSION.
B. The EXOSPHERE begins at an altitude of about 500 to 700 Km above Earth and extends out to INTERPLANETARY SPACE. At these altitudes, ATOMS and IONS are Very Far Apart. Some gases in the EXOSPHERE actually escape into SPACE. Particles of the SOLAR WINDS are concentrated into Radiation Layers at about 3000 and 16 000 Km above the Earth's Surface. These Layers of the EXOSPHERE are the VAN ALLEN BELTS and are held in place by Earth's MAGNETIC FIELD.
ATMOSPHERIC PREASURE
1. GASES of the Atmosphere, like all MATTER, have both VOLUME and MASS. Close to the Earth, the ATOMS and MOLECULES are PUSHED TOGETHER due to the Pressure of the MASS of Air above them. As the atoms and molecules become more closely packed, they exert more FORCE. Atmospheric Pressure is GREATEST at SEA LEVEL and DECREASES outward from Earth.
2. Air PRESSES DOWN on the Earth with a FORCE of 1 kg per square centimeter at SEA LEVEL. Air Pressure VARIES at different places at the same ELEVATION. This is caused by differences in AIR'S DENSITY. The are MORE MOLECULES of Air ABOVE a point having HIGH Pressure than above one where LOW Pressure is observed.
3. WARM AIR is LESS DENSE than COOL AIR, because the Air Molecules are FARTHER APART. Because TEMPERATURE AND ALTITUDE determine AIR PRESSURE, AIR PRESSURE Readings are useful in Predicting WEATHER and WIND CHANGES, and in Estimating ALTITUDES.
4. The FORCE of Air, or AIR PRESSURE is measured with a BAROMETER.
5. There are TWO kinds of Barometers, THE ANEROID AND THE MERCURY.
6. The ANEROID BAROMETER is a METAL BOX from with most of the Air is removed. The TOP of the Box is a THIN METAL DISK that BENDS under PRESSURE. As Air presses DOWN on the box, the DISK BENDS INWARD. The PRESSURE causes a SPRING to MOVE within the BOX. The SPRING is ATTACHED to a NEEDLE that shows the AMOUNT OF PRESSURE EXERTED BY THE AIR.
7. A MERCURY BAROMETER is more ACCURATE than an Aneroid, but a Mercury Barometer is too LARGE to be practical for many uses. A Mercury Barometer is made from a LONG TUBE Closed at ONE END. The Tube is filled with MERCURY and the OPEN END is placed UPRIGHT in a DISH OF MERCURY. When the Open End is placed in the Dish, A VACUUM forms between the CLOSED End of the tube and the TOP of the MECURY COLUMN. The HEIGHT of the MERCURY COLUMN is about 76 cm at SEA LEVEL. MERCURY moves UP and DOWN in the Tube depending on the AIR PRESSURE OUTSIDE. HIGH PRESSURE forces the Mercury in the Tube to RISE. LOW PRESSURE makes it DROP. When the Pressure INSIDE and OUTSIDE is EQUAL, the Mercury STOPS Moving.
HEAT
ENERGY FROM THE SUN
1. The SUN is the SOURCE of most of the Earth's SURFACE HEAT.
2. HEAT is TRANSFERRED as a result of a Difference in TEMPERATURE.
3. HEAT received from the SUN is transferred to different parts of Our Planet.
4. The SUN produces HEAT and LIGHT WAVES, which are a small part of the ELECTROMAGNETIC SPECTRUM. The Spectrum includes all ENERGY Forms, such as LONG RADIO WAVES, SHORTER X-RAYS, AND ULTRAVIOLET WAVES.
5. The ATMOSPHERE REFLECTS some ENERGY WAVES that reach Earth BACK into SPACE. The ATMOSPHERE ABSORBS some ENERGY. LAND AND WATER SURFACES ABSORB ENERGY that reaches the Earth's surface.
6. POLAR ICE Reflects the Sun's ENERGY and absorbs LITTLE of it. WATER also Reflects SOLAR ENERGY, especially when the Sun is near the Horizon. SAND and SNOW are other materials that tend to reflect SOLAR ENERGY.
7. VEGETATION, DARK ROCKS, AND BLACK SURFACES, such as ASPHALT Absorb LARGE amounts of SOLAR ENERGY. The ENERGY is then RETURNED to the Atmosphere as INFRARED RADIATION and HEAT.
8. WATER VAPOR and CARBON DIOXIDE in the Air absorb some of these INFRARED WAVES, and some of them are RE-EMITTED to Earth. This absorbed INFRARED ENERGY keeps HEAT in the TROPOSPHERE. The WARMING EFFECT is called THE GREENHOUSE EFFECT.
9. Earth's SURFACE and ATMOSPHERE LOSE HEAT when they are not FACING the SUN. LAND areas LOSE HEAT QUICKLY. WATER LOSES HEAT MORE SLOWLY. Earth would have Great differences in DAY and NIGHT TEMPERATURES if it were not for the ATMOSPHERE, which TRAPS HEAT and constantly moves it from one place to another.
10. Of 100% INCOMMING SOLAR RADIATION:
A. CLOUDS AND ATMOSPHERE Absorb 20 %.
B. 25% SCATTERED (REFLECTED) BY CLOUDS AND AIR
C. 5% REFLECTED BY THE EARTH'S SURFACE.
D. 50% IS ABSORBED BT THE EARTH'S SURFACE.
HEAT TRANSFER
1. There are THREE TYPES of HEAT TRANSFER; RADIATION, CONDUCTION, AND CONVECTION.
2. ENERGY from the SUN moves through space by RADIATION. RADIATION IS THE TRANSFER OF ENERGY BY MEANS OF ELECTROMAGNETIC WAVES. A campfire gives off Radiant Energy in the form of HEAT and INFRARED RADIATION.
1. RADIATION is an important process for transferring INFRARED RADIATION absorbed by Earth's SUFACE BACK to the ATMOSPHERE.
2.   CONDUCTION is the TRANSFER of HEAT THROUGH MATTER by the actual Contact of MOLECULES. Molecules are always in MOTION. HEATED MOLECULES move MORE RAPIDLY than COOLER MOLECULES. HEAT is transferred from Fast-moving Molecules to SLOW-Moving Molecules until ALL MOLECULES are moving at the SAME RATE.
3. A Stove HEATS a pan by CONDUCTION. CODUCTION also occurs at Earth's SURFACE as Heated Rocks or Sandy Beaches TRANSFER HEAT to the Surrounding AIR.
4. HEAT GAINED by the Atmosphere from RADIATION or CONDUCTION is usually transferred by CONVECTION. As AIR Absorbs ENERGY, its Molecules move FASTER and FARTHER Apart. This movement DECREASES the DENSITY of the AIR. COLD, Dense Air SINKS, FORCING WARM, LESS Dense air UPWARD.
5. This Transfer of HEAT due to DENSITY differences is called CONVECTION. CONVECTION Currents cause a constant EXCHANGE of COLD, Dense Air for LESS Dense Warm Air.   Many Home furnaces use THE CONVECTION PRINCIPLE for HEATING.
MOVEMENT OF AIR (WINDS)
1. Energy from the Sun warms the Atmosphere. Causing currents of ASCENDING and DESCENDING AIR OR WIND. WINDS distribute Energy around Earth's atmosphere.
2. Wind can blow from any Direction. WIND IS SIMPLY MOVING AIR. FORCES Cause the air to Move (Wind). One Type of FORCE that produces motion in air results from DIFFERENCES IN AIR PRESSURE.
3. A FORCE called the PRESSURE GRADIENT FORCE causes air to move from a region of HIGH Pressure to a REGION of LOW Pressure. Areas of HIGH and LOW Pressure form in the ATMOSPHERE as a result of changes in AIR TEMPERATURE AND DENSITY.
4. As soon as the PRESSURE GRADIENT FORCE starts air moving in the Atmosphere, the Earth's ROTATION begins to AFFECT it. Since the Earth ROTATES, air moving AWAY from a region of HIGH PRESSURE appears to turn toward the RIGHT in the NOTHERN HEMISPHERE and toward the LEFT IN THE SOUTHERN HEMISPHERE.
5. THIS APPERENT TURNING OF THE WINDS CAUSED BY THE EARTH'S ROTATION IS CALLED THE CORIOLIS EFFECT.
GLOBAL AND LOCAL WINDS
GLOBAL WINDS: DOLDRUMS, SUBTROPICAL HIGHS, TRADE WINDS, WESTERLIES, and POLAR ESTERLIES
1. The pattern of global winds is mainly Caused by the UNEVEN HEATING of the Earth. The area along the EQUATOR RECEIVES MORE DIRECT SUNLIGHT THAN THE POLESAND IS, THEREFORE, WARMER. Global winds are the general pattern of WIND Circulation in TROPOSPHERE-THE LAYER OF AIR IN, WHICH WE LIVE. Some daily variations in WIND Direction occurs at most places in the world, especially the LATITUDES OF THE WESTERLIES.
2. The North and South Poles have an average Temperature of -22 degrees C.
3. Temperature along the EQUATOR average 26 Degrees C.
4. This LARGE Temperature Difference causes Air to move by CONVECTION and CIRRCULATE between the Equator and the Poles. Large areas of HIGH and LOW Pressure form where air generally SINKS or RISES. These ZONES are called SEMI-PERMANENT because they are present most of the time.
5. DOLDRUMS. When air at the EQUATOR is WARMED, it becomes LESS DENSE and RISES. Since Air moves MOSTLY UPWARD here, WINDS Blowing along the SURFACE ARE Very LIGHT. Sailing Ships frequently STALLED for many days in this region, because of lack of WINDS.
6. The DOLDRUMS are a Windless Zone at the Equator. Here the air seems to be motionless, but actually it is being forced aloft (UPWARD).
7. TRADE WINDS: At about 30 Degrees Latitude, air currents DESCEND to EARTH'S Surface. The Trade Winds blow TOWARD the Equator and force the air of the DOLDRUMS to RISE. In the Northern Hemisphere, these winds blow from NORTHEAST to SOUTHWEST. In the Southern Hemisphere, the Trade Winds blow from SOUTHEAST TO NORTHWEST. The Trade Winds are named for the direction FROM which the BLOW.
8. THE WESTERLIES (PREVAILING WESTERLIES): These Wind blow from the Southwest to the Northeast in the Zone Between 30 and 60 Degrees Latitude in the Northern Hemisphere.   In the Southern Hemisphere, the WESTERLIES Blow from the NORTHEAST to the SOUTHEAST in this latitude zone.
9. The Westerlies are the WINDS Responsible for the movement of Weather Across the US and Canada.
10. POLAR EASTERLIES: These are COLD, DENSE, DRY, Horizontal Currents. Because the air at the poles is very Cold and Dense, an area of HIGH Pressure develops over the POLES. They move NORTHEAST to SOUTHWEST over the highest latitudes of the Northern Hemisphere. The Polar Easterlies move SOUTHEAST TO NORTHWEST in the Southern Hemisphere. Polar Zones are relatively small, but provide large amounts of ENERGY to the Zone of the WESTERLIES.
LOCAL WINDS: LAND, SEA, VALLEY, MOUNTAIN BREEZES
1. Land and Sea Breezes are types of local winds. During DAYLIGHT, the SUN Heats Land more QUICKLY than WATER. The process of CONDUCTION carries HEAT from the GROUND to the Air above it. As HEATED AIR RISESS, COOLER AIR FROM THE WATER Moves in to replace it. Since WINDS are NAMED for the DIRECTION from which they BLOW, This Movement of Air is a SEA BREEZE.
2. AT NIGHT, LAND COOLS MORE QUICKLY THAN WATER. The Air over the WATER is now WARMER then the Air of LAND. The WARMER Air RISES, and the COOLER Air moves off shore to take its place. This Flow of COOL Air from LAND to WATER is a LAND BREEZE.
3. Other Local Winds develop in Mountain Areas. During the DAY, The side of a Mountain that Faces the SUN HEATS MORE QUICKLY than the VALLEY BELOW. COOL Air in the Valley moves UP the Mountain to take the place of WARM AIR RISING. THIS FLOW OF AIR IS A VALLEY BREEZE.
4. At NIGHT, the Winds REVERSE. The Mountain COOLS More QUICKLY than the VALLEY. Air moves DOWN the Mountain to REPLACE RISING WARM Air from the Valley. THIS SITUATION PRODUCES A MOUNTAIN BREEZE.
JET STREAMS
1. A JET STREAM is a FAST-Moving River of Air up to 500 Km wide at the TOP of the TROPOSPHERE. The Speed of the JET STREAMS WINDS are as high as 370 Km per hour. The Jet Stream FLOWS from WEST to EAST over the US.   There are TWO Jet Streams that Flow over the US (or each Hemisphere). The Jet Stream changes their position in Latitude and Altitude from Day to Day.