ES 5.1 PPT
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ES 5.1 PPT






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ES 5.1 PPT ES 5.1 PPT Presentation Transcript

  • Composition of theAtmosphere The atmosphere is a mixture of gases surrounding Earth.  Nitrogen (78%), the most common atmospheric gas, is released when dead plants and dead animals break down and also when volcanoes erupt.  Oxygen (21%), the second most common atmospheric gas, is made by phytoplankton and plants.  The remaining 1% of the atmosphere is made up of argon, carbon dioxide, water vapor and other gases.
  • Atmospheric Pressure Gravity pulls gas molecules toward Earth, causing atmospheric pressure, which is the force per unit area that is exerted on a surface by the weight of the atmosphere.  Strongest at Earth’s surface  more air is above you.  Avg. pressure at sea level can be expressed as any of the following: ○ 1013.2 millibars (mb) ○ 1 atmosphere (atm) ○ 760 mm. Hg (mercury) ○ 30 inches Hg (mercury)
  • Layers of the Atmosphere The Earth’s atmosphere is divided into four layers based on temperature. The name of each layer gives you clues about its features:  Troposphere (tropo = turning or change)  Stratosphere (strato = layer)  Mesosphere (meso = middle)  Thermosphere (thermo = heat)
  • Troposphere Lowest layer of the atmosphere, lying next to Earth’s surface. Temperature decreases with altitude. Contains almost 90% of the atmosphere’s mass. Nearly all weather occurs in this layer. The zone known as the tropopause represents the upper boundary of the troposphere.
  • Stratosphere The atmospheric layer above the troposphere. Lower stratosphere is extremely cold, but temperature increases as altitude increases in the stratosphere.  Rises because ozone, (O3), in the stratosphere absorbs UV radiation from the sun, warming the air  protects life on Earth. The zone known as the stratopause represents the upper boundary of the stratosphere.
  • Mesosphere  The middle layer of the atmosphere.  Coldest layer as well.  Temperature decreases as altitude increases, just like the troposphere.  The zone known as the mesopause represents the upper boundary of the mesosphere.
  • Thermosphere Uppermost atmospheric layer. Temperature again increases steadily with altitude because nitrogen and oxygen atoms absorb solar radiation.  This releases thermal energy. No data to determine its upper boundary.  Blends with the vacuum of space (exosphere).
  • Ionosphere The lower part of the thermosphere is considered the Ionosphere. As a result of N2 atoms and O2 atoms absorbing the radiation, temperature in the thermosphere rises, and gas particles become electrically charged  ions. Ions within the ionosphere can radiate energy as shimmering lights called auroras, a.k.a. the Northern and Southern Lights.
  • Radiation The Earth receives energy from the sun by radiation, which is the transfer of energy as electromagnetic waves move through space.  The sun radiates enormous amounts of energy, but the Earth only receives about two-billionths of this energy.  This small amount still drives weather cycles and makes the Earth a habitable environment.
  • Conduction If you ever got burned when you touched something hot, you have experienced another form of energy transfer. Conduction is the transfer of energy through contact of one object to another object.  Thermal energy is always transferred from warm to cold areas.  When air molecules come in direct contact with the warm surface of the Earth, thermal energy is transferred to the atmosphere.
  • Convection The transfer of energy by the circulation, or movement, of a liquid or gas is known as convection.  Most thermal energy in the atmosphere is transferred by convection. ○ Warm air rises, cool air sinks.  Convection should also sound familiar to you from talking about Earth’s interior. ○ Warm material rises, cool material sinks.
  • The Radiation Balance For Earth to remain habitable for humans, the amount of energy received from the sun needs to balance the amount of energy returned to space.  Solar energy absorbed by Earth is eventually reradiated into space as thermal energy. Every day, the Earth receives more energy from the sun. The balance between incoming energy and outgoing energy is known as the radiation balance.  Out of the incoming solar radiation from the sun: ○ About 25% is reflected and scattered by clouds and air. ○ About 5% is reflected by Earth’s surface. ○ About 20% is absorbed by clouds and the atmospheric gases. ○ About 50% is absorbed by Earth’s surface.