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Atmosphere The atmosphere is that layer of air that surrounds the Earth. It protects is from solar radiation. It provides living things with gas that they need to live (ex: CO2 for plants, Oxygen for humans & animals). The atmosphere maintains a temperature on the earth so live can exist. Without the atmosphere the temperature on earth would be -18oC. 99% of the gases are in the first 30km above the surface of the Earth. The Atmosphere extends more than 10 000km. The atmosphere is composed of: 78% nitrogen 21% oxygen The other 1% is composed of all the other gases (0.38% CO2, 0.4% water vapor, 0.000 001% Ozone etc…) Atmospheric Pressure Gravity pulls the gases towards Earth. Because of gravity most of the air molecules are close to the earth, therefore there’s a higher pressure at a lower altitude. The higher into the atmosphere you go, the less air molecules therefore the lower the pressure. The pressure at the surface is 14.7 pounds whereas at the top of Mount. Everest the pressure is 4.5 Layer of the Atmosphere 1. Troposphere: From the surface 10-15km Most clouds and storms occur in this layer The temperature drops with altitude (the higher up you go, the temperature is colder in this layer) Where weather happens Contains most of our air Contains all life Where planes fly 2. Stratosphere: 15-50km Is the ozone layer It contains all the ozone which absorbs UV rays Protects us from these rays As you go up in this layer, the temperature gets hotter due to the fact that is absorbs the UV rays 3. Mesosphere: 50-80km Contains meteors Contains stars Contains very little air particles It’s very cold 4. Thermosphere: 80-500 km It is the hottest layer in the atmosphere (up to 2000 degree) because it absorbs fmost of the sun’s radiation but it would not feel hot to us because of the rarity of air particles Contains the Aurora borealises 5. Exosphere: 500-10 000km Its empty, outer space Satellites orbit earth in this layer Atmospheric Circulation It is driven by the rotation of the earth & convection. Convection warm air at the equator rises and travels to the poles. Cold air moves south closer to the surface. The combination of convention & the Earth’s rotation causes the Coriolis effect. Air moves in curved paths. Predicting weather There is a fair amount of randomness when predicting weather this is called the Butterfly effect. Air circulates in loops. These loops are called cells. There are three cells called: Hadley, Ferrel & Polar. The Hadley cell spans the equator. The Ferrel cell circulates over Canada & the States. The Polar air transports the coldest air and is near the poles. The circulation is driven by the rising of warm of air and the sinking of cold air (convection) Prevailing winds (polar easterlies, westerlies & the trade winds) are created and they move in predictable directions based on the Coriolis effect. (longitudes horizontal, latitudes vertical) Trade winds are easterly (east to west), from the equator, NEAR the equator. Westerlies blow from the west to the east. Polar easterlies blow from the east to the west. Air Masses Large volumes of air that are uniform temperature (1-2o F) and humidity are called air masses. Quebec receives warm, moist air masses from the south & cold, dry air masses from the North. When two air masses meet, a Front is created. When cold air is moving there is a cold front and when warm air is moving there is a warm front. Remember that a cold front is dense, therefore it pushes the warm front up. Cold front cold air pushes the warm air up. The warm, moist air condenses resulting in rain & thunderstorms. They are represented with blue line with arrows Warm front warm air slides over a cold front causing precipitation. Represented with a red line with semicircles. Anticyclones & Depressions They are caused by the rise and fall of vertical air. When warm air rises a depression is created. Depression is the low air pressure left behind when warm air rises. Depression is basically the rain and wind before a cyclone…depressions could become hurricanes Convection currents form around the rising air in hurricanes & the earth’s rotation is what spins a hurricane. (wind can be over 350km/h & the diameter of the hurricane can be over 1500km) Anticyclone (high pressure zone). Created when cold air drops vertically. It is associated with blue skies that are sunny and clear. (represented with a H) High pressure brings moist, warm, sunny weather. Low pressure brings rainy, dry, cold weather (even hurricanes, tornadoes….) The Greenhouse Effect Most of the Sun’s rays that reach the Earth’s surface are absorbed by the ground. The ground emits infrared rays that get trapped into the atmosphere while others get lost in space. Greenhouse gases retain some of these rays and retransmit them back to Earth. Water vapor, Carbon dioxide, Methane & Ozone contribute the most to the greenhouse effect. The Greenhouse effect makes Earth’s climate liveable but…. As more greenhouse gases are being emitted in to the air, Earth’s climate is getting warmer which will cause many problems (glaciers melting, sea levels rising, floods, more skin cancer cases) CO2: emitted from burning fossil fuels & cutting forests Methane: released from cow farts & decomposing waste Nitrous oxide: emitted by nitrogen rich fertilizers CFC: destroy the ozone layer Nitrogen & Sulfur dioxide cause acid rain. Metals such as mercury are harmful for humans. Earth’s temperature has risen by 0.76oC in the last 150 years and it is said that a rise of 2o in temperature will cause environmental problems. CFCs were used in arsenols & refrigerators. When these gases are emitted into the atmosphere they destroy ozone by releasing chlorine. The Ozone Layer is thinning which is a huge problem because it blocks the ultra violet radiation from the sun, this radiation can cause damage to living things (skin cancer). In 1987 CFCs were banned. Smog Ozone is good and bad. It is good because it absorbs UV rays but if too close to the surface ozone can be harmful. Pollution from industries & vehicules (nitrogen oxide) reacts with the sun’s rays to form ozone, close to the surface of the Earth. When ozone is mixed with smoke and fog it creates smog. Smog can cause lung damage. Energy from Air Wind energy: wind is a renewable source. Energy from the wind can be captured by wind turbines. A wind turbine produces 2 megawatts of power which is enough to supply 2000 houses. The only problem is that the wind is not constant therefore a combination of energy types will be needed. Effect of the Sun & Moon on Earth The sun is created of hydrogen (78%) & helium (25%). Gravity and nlucear fusion at its core turns the hydrogen into helium (which produces the sun’s rays). Energy from the sun is electro-magnetic. Because the Earth is curved (in the shape of a circle) the sun rays heat the surface unevenly. This difference drives the circulation of the hydrosphere & atmosphere. (causes wind) Ways to capture solar energy: passive heating, solar panels & solar collectors. Passive heating the sun rays heat up “heat sinks” (concrete, walls). These heat sinks heats up a space at night. Solar panels when sun rays hit sillicons, electrons flow. (can power appliances, or charge batteries) Solar collectors flowing water or in oil in pipes collect’s the suns heat. This heat is then transferred to another location. ( ex: to heat up swimming pools) The Moon Created 4.6 billion years ago when Theia hit Earth. The Moon and the Earth have a gravitational pull between each other, which causes the Earth and its water to always lean towards the moon. When water is leaning towards the moon, it creates tides. There are atleast two high and two low tides per days. When the sun is in line with the moon it adds to the effect the moon has on Earth (high tides) When the sun is at right angles of the moon it reduces the effect the moon has on Earth (low tides) The energy of tides can be used to generate energy (tidal energy captured by tidal turbines) REVISION The Cryosphere It includes all the frozen water on Earth’s surface. Glacier, snow, icebergs Sea ice Pack Ice: Pack ice expands & contracts. It is a seasonal change. Pack ice is basically frozen ocean surfaces. Pack ice break off into huge pieces and become ice floes. The extent of pack ice decreased (because of global warming & increasing carbon dioxide levels) Glaciers: Buildup of snow on land at the poles. The pressure turns the snow into ice. Many of the glaciers have been melting. As they melt they slide off the land and could rise sea levels. They can also disrupt the thermohaline circulation, which can mess up Earth’s climate.