Download Atmosphere Notes

Thursday, November 12, 2015
The Atmosphere
Chemical Composition of the Earth’s Atmosphere
- Use the chart in the ESRT on page 1 to view the chemical composition of the
Atmosphere
• This table lists not only the Troposphere, the lowest section of the Atmosphere
where weather occurs, but the Crust (Lithosphere) and the Hydrosphere
Selected Properties of Earth’s Atmosphere
- Use the chart on page 14 of the ESRT
- Altitude above sea level is shown on the left in both Miles and Kilometers
- Temperature Zones through the different layers are shown in degrees Celsius
• the location of the change in layers corresponds to the change in temperature
• the areas where the zones are separated are called “pauses” tropopause,
stratopause, Mesopause)
- Atmospheric pressure is listed and the units in which it is measured are called
atmospheres
• at sea level the pressure is 1 atmosphere and it decreases through the layers
- Water Vapor concentration is the last section, and shows a decrease as you go higher
in the atmosphere
• Almost all of the water vapor concentration is found in the atmosphere is found in
the Troposphere
Moisture in the Atmosphere
- Dew Point is the temperature at which moisture condenses out of the air
• it is always colder, or equal to, the temperature of the air
• It can be calculated using a tool called a Sling Psychrometer and page 12 of the
ESRT
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Thursday, November 12, 2015
- A sling psychrometer measures the air temperature using a dry thermometer as
well as the temperature of a wet bulb (thermometer with a wet sock), which
measures the rate of evaporation
• the more moisture in the air, the closer the wet bulb will be to the dry bulb
• the dryer the air, the greater the difference between the wet and dry bulbs
- The difference between the two temperatures is used in the chart to calculate the
Dew Point temperature
• On the left side of the chart, use the dry bulb (air temperature)
• At the top use the difference between the two thermometers.
• The answer will be in ºC
- Relative Humidity is the amount of moisture an air mass can hold
• it is a percentage out of 100%
- when the air is saturated, it can’t hold any more moisture in the gaseous phase,
so clouds,fog and/or precipitation occurs
• Just like when measuring Dew Point, a sling psychrometer is the instrument that is
used, but a different chart is used
• Use the lower chart on page 12 of the ESRT to determine the Relative Humidity (%)
- If given an air temperature and a Dew Point, one should be able to work backwards
and determine the Relative Humidity of an air parcel
• Warm air is able to hold a larger amount of water than cold air
Temperature Conversions
- Use page 13 of the ESRT to convert a temperature from one unit to another
• ºC <——> ºF
or
ºF <——> K
or º C <——> K
• Be aware of the scale for each unit, ºC and K increase by 1º/line and ºF increases
by 2º/line
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