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18.1 atmosphere

Published on Dec 01, 2015

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PRESENTATION OUTLINE

18.1 Water in the Atmosphere

By: Vanessa Ward

Precpitation

  • Any form of water that falls from a cloud.
  • Clouds, fog, rain, snow sleet, and hail are examples of Precpitation.
  • When it comes to understandig atmospheric processes, water vapor is the most important gas in the atmopshere
Photo by VinothChandar

Latent heat

  • Latent means "hidden" like the latent fingerprints hidden at a crime scene.
  • The used to melt ice doesnt produce a temperature change, so its refered to as Latent heat.
  • Latent heat plays a crucial role in many atmospheric processes. For example, the release of latent heat aids in forming the towering clouds often seen on warm summer days
Photo by Piero...

Evaporation

  • The process of changing a liquid to a gas
  • The energy absorbed by the water molecules during evaporation gives them the motion needed to escape the surface of the liquid and become a gas.
  • This energy is referred to as latent heat of vaporization.
Photo by Dru!

Condensation

  • The opposite process where water vapor changes to the liquid state
  • In the atmosphere, condensation generates clouds and fog.
  • For condensation to occur, water molecules must release their stored heat energy, called latent heat of condensation, equal to what was absorbed during evaporation
Photo by Domiriel

Sublimation

  • is the conversion of a solid directly to a gas, without passing through the liquid state.
  • You may have observed this change in watching the sublimation of dry ice, or frozen carbon dioxide.
  • Dry ice sometimes is used to generate “smoke” in theatrical productions.
Photo by mike.warns

Deposition

  • is the reverse process, the conversion of a vapor directly to a solid.
  • This change happens when water vapor is deposited as frost on cold objects such as grass or windows.

Humidity

  • The general term for the amount of water vapor in air
  • Meteorologists use several methods to express the water-vapor content of the air.
  • These include relative humidity and dew-point temperature.
Photo by Andrew.T@NN

Saturated

  • The amount of water vapor required for saturation depends on temperature
  • When saturated, warm air contains more water vapor than saturated cold air

Relative Humidity

  • Relative humidity is a ratio of the air’s actual water-vapor content compared with the amount of water vapor air can hold at that temperature and pressure.
  • Relative humidity indicates how near the air is to saturation, rather than the actual quantity of water vapor in the air.
Photo by jenny downing

Dew point

  • The dew-point temperature or simply the dew point is the temperature to which a parcel of air would need to be cooled to reach saturation.
  • If the same air was cooled further, the air’s excess water vapor would condense, typically as dew, fog, or clouds.
Photo by ecstaticist

Hygrometer

  • Relative humidity is commmonly measured by using a hygrometer.
  • One type of hygrometer, called a psychrometer, consists of two identical thermometers mounted side by side.