Chapter 15-atmosphere
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Chapter 15-atmosphere






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Chapter 15-atmosphere Chapter 15-atmosphere Presentation Transcript

  • Chapter 15 Atmosphere
  • Earth’s Atmosphere
    • Earth’s atmosphere, is a thin layer of air that forms a protective covering around the planet.
    • The atmosphere maintains a balance between the amount of heat absorbed by the sun and the amount of heat that escapes back out into space.
    • It also, gives Earth’s life forms protection from the sun’s UV rays.
  • Makeup of the atmosphere
    • The atmosphere is a mixture of gases, solids, and liquids that surround the planet, and it extends from the surface of the earth to outer space.
    • The original atmosphere of earth is said to have been made up of CO2, and nitrogen, but very little oxygen.
    • As organisms, like bacteria, evolved they began to release oxygen as a by product, when they made food through photosynthesis.
  • Makeup of the atmosphere
    • As time went by the top layer of the atmosphere became very rich in ozone (O 3 ), and allowed green plants to flourish.
    • This flourishing of plants gave an even larger output of oxygen, and aided in the evolution of other organisms.
    • Today, 78% of the gas in the atmosphere is Nitrogen, and only 21% is oxygen.
    • The other 1% includes water vapor, carbon dioxide, methane, and ozone.
  • Makeup of the atmosphere
    • The atmosphere also contains small, solid particles of dust, salt, and pollen.
    • The dust is picked up by wind along with pollen, and the salt is picked up in ocean mist.
  • Lower Layers of the Atmosphere
    • The lowest layer of the atmosphere, where almost all of your activity takes place is called the troposphere.
    • It has 99% of all the water vapor, and 75% of all the other atmospheric gases. All of our weather and clouds occur in the troposphere.
    • The layer above the troposphere is called the stratosphere and is 11km above the surface and extends to 50km. The ozone layer is located in this layer of the atmosphere.
  • Upper Layers of the Atmosphere
    • Above the stratosphere is the mesosphere, which acts to absorb the suns energy.
    • Next, is the Thermosphere, which is the thickest layer, and has very high temps due to its proximity to the sun.
    • Within the mesosphere and thermosphere is what is called the ionosphere, which is a layer of electrically charged particles.
    • The ionosphere allows radio waves to travel from one place to another.
  • Exosphere
    • The exosphere starts at the top to the thermosphere and continues until it merges with space. In this region of the atmosphere, Hydrogen and Helium are the prime components.
    • This is the atmosphere that our space shuttles orbit the earth.
    • H.W. 433 pg 1-4 & pg 448 1-5
  • Atmospheric Pressure
    • Atmospheric gases extend hundred kilometers above the Earth. Earths gravity is responsible for pulling these gases down toward the surface.
    • It is the weight of these gases, due to gravity, that pushes down on the air in the troposphere and is known as atmospheric pressure.
    • As you go up in altitude there is less atmospheric pressure because you have less atmospheric layers above you, pushing down on you.
  • Atmospheric Temperature
    • Temps of the thermosphere are very high because it is directly exposed to the suns energy. As the suns energy passes through the thermosphere temps slowly decline.
    • The troposphere could have high temps as well. This is due to the sun warming the surface of earth, which then warms the air in the troposphere.
  • The ozone layer
    • The ozone layer is held in the stratosphere, and contains ozone gas, which is 3 oxygen molecules.
    • This layer shields us from the UV rays from the sun, which could cause skin damage, ike melanoma.
    • Pollutants, like car exhausts expel things called chlorofluorocarbons which take an O from the O 3 molecule and destroys the ozone layer.
    • When we speak of a hole in the ozone layer, we actually mean that a hole in the atmosphere exists that is allowing harmful amounts of UV light to reach the surface of the earth.
  • Energy transfer in the Atmosphere
    • The Sun provides most of earths energy, and when the suns energy is received by the Earth 3 things could happen:
    • Some energy is reflected back into space by clouds.
    • Some is absorbed by the atmosphere
    • Some is absorbed by the surface of the earth.
  • Heat energy
    • Heat is the transfer of thermal energy from an object with a higher temp to one with a lower temp.
    • This transfer of thermal energy occurs in three ways:
    • 1) Conduction- this is the transfer of heat from one molecule to another through physical contact.
    • If you put a spoon into a hot bowl of soup, the spoon will get warmer because it conducts heat from the hot soup.
  • Heat energy
    • Radiation- this is thermal energy that moves away from its source in all directions in the forms of waves. Ex: The suns energy and a microwave oven uses radiation to heat things with thermal energy.
    • Convection is the transfer of heat by currents within a fluid or a gas.
    • Ex: hot air rising off the surface of a radiator.
  • The water cycle
    • All of the water that is part of Earth is called the hydrosphere.
    • There is a constant cycle of water between the atmosphere and the hydrosphere that plays a big role in determining weather patterns and climates.
    • Bodies of water evaporate due to the suns energy and enter the atmosphere as water vapor.
    • When the water vapor cools it returns to earth as liquid in the form of rain or solid snow.
    • That cooling process of water vapor is called condensation.
  • The water cycle
    • When condensation occurs very high with in the atmosphere, clouds form.
    • Clouds are made of tiny water droplets that eventually collide with other tiny water droplets to form rain.
    • The rain that falls from clouds is called precipitation. And completes the water cycle.
    • H.W pg 438 pg 438 ques. 1-4
    • pg 448 ques 6-15
  • Air Movement
    • Because of certain surface features, Earth gets heated unevenly by the sun. This causes warmer air is some places and cooler air in other places.
    • When air is heated it expands and is considered to be a low pressure system.
    • When air is cooled it contracts and is considered to be a high pressure system.
    • Wind is the transfer of high pressure air to an area of low pressure air.
  • Air Movement
    • So, cold air from the poles moves toward the hot air near the equator in the form of convection (wind) currents.
    • The earths rotation causes the deflection of air in different directions. Wind moving north above the equator is deflected to the right.
    • Air moving south below the equator is deflected to the left.
  • Global winds
    • Sea breeze- these are winds that blow from the sea or ocean over land, during the day. This occurs b/c during the day the land is heated more than the water and the high pressure air over the water moves to the lower pressure air over the land.
    • Land breezes- are the complete opposite of sea breezes and occur at night. This occurs b/c at night the land cools faster than the water.
    • H.W. due next class on looseleaf pg 450 ques 1-19
  • Test one Week