Skip to main content

Dew Point Explained !!

                                             Why do cold drinks sweat in hot weather ?



The dew point is the temperature at which water vapour condenses into liquid water , ie. it is the temperature at which the air can no longer "hold" all of the water vapor which is mixed with it, and some of the water vapor must condense into liquid water.
The dew point is a reflection of the humidity. The dew point of humid air will be higher than the dew point of dry air. When air has reached the dew-point temperature at a particular pressure, the water vapor in the air is in equilibrium with liquid water, meaning water vapor is condensing at the same rate at which liquid water is evaporating.




Below the dew point, liquid water will begin to condense on solid surfaces (such as blades of grass) or around solid particles in the atmosphere (such as dust or salt), forming clouds or fog.
In technical terms, the dew point is the temperature at which the water vapor in a sample of air at constant barometric pressure condenses into liquid water at the same rate at which it evaporates. The condensed water is called dew when it forms on a solid surface, or frost if it freezes. In the air, the condensed water is called either fog or a cloud, depending on its altitude when it forms. 
A higher dew point means there is more moisture in the air. A very high dew point can indicate severe weather. A high dew point means that the air is unstable and that thunderstorms may develop. Also While relative humidity is a relative measure of how humid the air is, the dew point temperature is an absolute measure of how much water vapor is in the air.
Increasing the barometric pressure increases the dew point. This means that, if the pressure increases, the mass of water vapor in the air must be reduced in order to maintain the same dew point. 
Water will condense as liquid on any surface that has a temperature below the dew point. If the surface temperature of your cold glass is below that of the dew point, you will have water condensing on it. The exact same sequence of events causes dewdrops to form on plant leaves.

                                                 

Comments

Post a Comment

Popular posts from this blog

Bay,Gulf,Strait,Isthmus,Peninsula Explained !!

∎ Bay ➤ A bay is a body of water that is partly surrounded by land. Bays empty out into larger bodies of water like oceans and lakes. They are sometimes confused with other bodies of water such as gulfs, but bays are typically smaller . There are various ways in which bays can form. The largest bays have developed through plate tectonics. As the super-continent Pangaea broke up along curved and indented fault lines, the continents moved apart and left large bays; these include the Gulf of Guinea, the Gulf of Mexico, and the Bay of Bengal, which is the world's largest bay. Bays also form through coastal erosion by rivers and glaciers. A bay formed by a glacier is a fjord. Rias are created by rivers and are characterized by more gradual slopes. Bays can also be found along the shores of lakes. Bays are usually much calmer and more protected than seas or oceans . The land surrounding a bay often reduces the strength of winds and blocks waves. Most bays make excellent harbors and m...
Post a Comment
Read more

Anabatic and Katabatic winds

                              Anabatic = moving upwards ;    Katabatic = moving downwards . Anabatic winds which  flow upslope of a mountain from lower valleys  develop during daytime in calm sunny weather. They are    warm winds which blows up a steep slope or  mountain  side, driven by heating of the slope through  insolation .   Air which is in contact with slopes that are warmed expands upward and cool and sinks over neighbouring valleys. Anabatic winds are usually slow , at only 1-2m/s and are rarely important expect near coasts where they can increase the strength of sea breezes.   Anabatic winds are particularly useful to soaring  glider  pilots who can use them to increase the aircraft's altitude. Anabatic winds can be detrimental to the maximum downhill speed of cyclists.      Katabatic winds a...
Post a Comment
Read more