11.28.16 Water Vapor in the air
figure 19.1
As air cools it loses the ability to hold water vapor.
Humidity: how much water vapor is in the air.
Relative humidity: a measure of­ how much water vapor is in the air
how much water vapor the air can hold
Saturation: when air is holding all (100%) the water vapor it can. 100% relative humidity.
Dew Point Temperature (DPT): the temperature at which air becomes saturated (or reaches 100% relative humidity.)
If the air is saturated and a surface is present, condensation will occur.
In nature: surface is called Condensation Nuclei.
Research Question:
What is the Dew Point Temperature of the Earth Lab, today, during this class?
Procedure:
measure temperature of water before adding one ice cube
measure temperature every 30 seconds
when cube melts add another (include this on data table)
when condensation is noted/observed continue for two more temperature measurements
Sling Psychrometer: tool (used by meteorologists to measure DPT).
Dry Bulb
Wet Bulb
finished lab due Fri
1
11.28.16 Water Vapor in the air
figure 19.1
Saturation: when air is holding all the water vapor that it can (100% humidity).
As air cools it loses the ability to hold water vapor.
Relative Humidity: a ratio of: the amount of water vapor in the air
the amount of water vapor the air can hold
Dew Point Temperature (DPT): temperature at which the air becomes saturated (reaches 100% relative humidity.)
Condensation Nuclei: the natural surfaces upon which condensation occurs to form cloud particles.
Research Question:
What is the Dew Point Temperature of the Earth Lab, today, during this class?
measure temperature every 30 seconds
after first temp reading insert an ice cube
keep measuring temp/time
when an ice cube melts replace it
note what time/temp condensation occurs (DPT)
make two more temp readings after DPT is reached.
Sling Psychrometer: a tool used by meteorologists to measure Dew Point Temperature.
10.5
13
10
9
10
9.8
Dry Bulb
­Wet Bulb
Wet Bulb Depression
2
11.28.16 Water Vapor in the air
figure 19.1
p358
Humidity is a measure of water vapor in the air.
saturation
humidity
relative humidity
dew point temperature
condensation nuclei
As air cools it loses the ability to hold water vapor.
Relative Humidity: a ratio of­ how much water vapor is in the air
how much water vapor the air can hold
Saturation: when air is holding all water vapor that it can, 100% relative humidity.
If air is saturated AND a surface is present, then condensation will occur.
this occurs at Dew Ppint Temperature (DPT)
Condensation nuclei
little droplets
Research question: at what temperature does the air in the Earthlab become saturated with water vapor?
­measure temperature every 30 seconds
­after first temp reading insert an ice cube
­keep measuring temp/time 30 sec intervals
­when an ice cube melts replace it
­note what time/temp condensation occurs (DPT)
­make two more temp readings after DPT is reached.
Using the Sling Psychrometer:
a tool which a meteorologist uses....
dry bulb
­wet bulb
wet bulb depression
3