moisture in the atmosphere, humidity, temperature and dewpoint
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Moisture in the atmosphere, HUMIDITY, TEMPERATURE AND DEWPOINT. RRB Pg 117. Moisture in the atmosphere. Saturation: When the air contains as much moisture as it can hold The higher the temperature, the more moisture air can hold - PowerPoint PPT PresentationTRANSCRIPT
RRB Pg 117
Saturation: When the air contains as much moisture as it can hold
The higher the temperature, the more moisture air can hold
If air temperature of moist air is lowered enough, the air will become saturated
If the temp falls below the dew point, water vapor usually turns into liquid water
Moisture in the form of water vapor enters the atmosphere by evaporation, sublimation to a gas, and transpiration
Evapotranspiration: Evaporation and Transpiration together
Large amounts of energy are needed to change liquid water into water vapor during evaporation and transpiration, most of which comes from insolation
EUREKA!! Transpiration- a flashback to biology
Sling psychrometer: has two thermometers mounted so they can be slung through the air. One thermometer records air temp (dry bulb temp) and the other has a wet cloth which measures the wet bulb temp
Evaporation causes cooling The drier the air, the greater the
evaporational cooling, the greater the difference between the dry-bulb and wet-bulb temps
Use a dew point temperature table to determine the dew-point. ESRT pg 12
Dew point is expressed using a unit of temperature (Celsius or Fahrenheit)
Dew point: the temp to which air must be cooled to become saturated
The only way to change the dew point is by adding or removing moisture from the air
Locate the dry-bulb (air temperature) reading on the left hand side of the chart
Subtract the wet-bulb reading (measure of how dry or saturated the air is) from the dry-bulb reading
Locate the difference between the wet-bulb and dry-bulb readings across the top of the chart
Follow the horizontal row for the dry-bulb reading to the right until it meets the vertical column running down from the difference between the wet-bulb and dry-bulb readings
If the dry-bulb temperature is 8 degrees Celsius and the wet-bulb temperature is 2 degrees Celsius, find the dew point
Note that the wet-bulb temp will always be the same or colder than the dry-bulb
If the dry-bulb temperature is 26 degrees Celsius and the wet-bulb temperature is 25 degrees Celsius, find the dew point
Relative humidity: the ratio of the amount of water vapor in the air (absolute humidify) to the maximum amount it can hold (moisture capacity)
Relative humidity is expressed as a percent of saturation
Air that is saturated = 100% To determine RH, you need a sling
psychrometer and a RH table- ESRT 12
If the RH is 50%, the air could contain twice as much water vapor
As the temperature of the air approaches the dew point, the relative humidity approaches 100%
Locate the dry-bulb reading on the left-hand side of the Relative Humidity chart
Subtract the wet-bulb reading from the dry-bulb reading
Locate the difference between the wet-bulb and dry-bulb readings across the top of the chart
Follow the horizontal row for the dry-bulb reading to the right until it meets the vertical column running down from the top
1. Find the RH when the dry-bulb temperature is 18 degrees Celsius and the wet-bulb temperature is 13 degrees Celsius
2. Find the RH when the dry-bulb temperature is 10 degrees Celsius and the wet-bulb temperature is 9 degrees Celsius