The dew point is the temperature at which the air must be cooled for water vapor in the air to condense into liquid water. When the air temperature cools to the dew point, the relative humidity reaches 100% and condensation occurs in the form of dew, fog, or clouds. An example is provided of air at 15°C containing water vapor; as it cools to 10°C, its relative humidity increases until it reaches 100% saturation at the dew point temperature.

1. 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

2. 15C
• Shown here is the parcel of air, which is at 15C
and has certain amount of water vapor inside.

3. 11C13C
• 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.

4. 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.

5. • 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.

6. 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%.

7. 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.