Dew Point

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DEW POINT
• The temperature where
relative humidity reaches a
100%, that is the temperature
in which saturation occurs is
known as Dew Point
temperature.
• In simple words, the
temperature to which moist air
must be cooled to reach
saturation.
• For e.g. condensed water is
called dew, when it forms in a
solid surface
15C
• Shown here is the parcel of air, which is at 15C
and has certain amount of water vapor inside.
13C
11C
• Look at the image and notice that now when
parcel of air is cooled , its capacity to hold water
vapor reduces and relative amount moisture of air
increases.
• In other words, its relative humidity is increasing.
10C
• When 10C is reached, parcel of air is holding as much
water vapor as it can and is therefore saturated.
• The relative humidity is 100%.
• This temperature is the dew point temperature.
• If parcel of air were to cool
further, condensation would
occur, because the air can
hold no more water vapor at
this temperature.
• This condensation is visible
to us because clouds and fog
will form as visible water
droplets condense out of
the saturated air.
An Example
• If the air temperature
cools to the dew point, or
if the dew point rises to
equal the air
temperature,
then dew, fog or clouds b
egin to form. At this point
where the dew point
temperature equals the
air temperature, the
relative humidity is
100%.
4 Steps To Create Dew Point
• You will need an aluminum
beverage can, cutter or blade,
water and a lot of ice cubes.
• Cut a shiny aluminum beverage can
in half and preserve the bottom
portion for use as a receptacle.
• Fill the can with tap water.
• Add ice cubes to the water to
effectively lower the can’s surface
temperature. Stir the mixture
gently and keep adding ice until
condensation forms on the can’s
exterior surface.
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