11.2 State of the Atmosphere
Temperature Versus Heat
Temperature- a measurement of how rapidly or slowly
Heat- the transfer of energy that occurs because of a difference in temperature between substances
The direction of heat flow depends on temperature.
Heat is the transfer of energy that fuels atmospheric processes, while temperature is used to measure and interpret that energy.
Measuring Temperature
Can be measured in Fahrenheit(F) or Celsius(C).
The Kelvin scale measures the number above zero, which corresponds to approximately -273degrees C and -523degrees F. This scale is a more direct measure of molecular activity, because at absolute zero, molecular motion theoretically stops.
Dew Point
Dew point- is the temperature to which air must be cooled at constant pressure to reach saturation.
Saturation is the point at which the air holds as much water vapor as it possibly can.
Condensation- when matter changes state from a gas to a liquid
Vertical Temperature Changes
Dry adiabatic lapse rate- the rate at which unsaturated air to which no heat is added or removed will cool.
Lifted condensation level- the height at which condensation occurs
Air Pressure and Density
Atmospheric pressure decreases with height because there are fewer and fewer gas particles exerting pressure.
The density of air is proportional to the number of particles of air occupying a particular space.
Pressure-Temperature-Density Relationship
Pressure increases or decreases, so does temperature. Temperature increases or decreases, so does pressure.
Temperature increases, density decreases. Density increases, temperature decreases.
Temperature Inversions
Temperature Inversion-is an increase in temperature with height in an atmospheric layer.
The Temperature-altitude relationship is inverted or turned upside down.
Wind
Cool air, being more dense, sinks and forces warm, less dense air upward. In the lower atmosphere, air generally moves from areas of high density to areas of low density. The air moves in response to density imbalances created by the unequal heating and cooling of Earth’s surface. These imbalances create areas of high and low pressure.
Near earth’s surfaces, wind is disrupted by the friction that results from its contact with trees (etc). Father up, there is nothing to disturb the wind and there is less friction, increasing wind speeds.
Relative Humidity
Humidity- the amount of water vapor in the air
Relative Humidity- the ratio of water vapor in a volume of air relative to how much water vapor that volume of air is capable of holding
RH is expressed in percentage. If a certain volume of air is holding as much water vapor as it possibly can, its RH is 100%.
Tags: