What's the differnce between wet bulb and dry buld temperatures and what are their physical significance?

Answer 1

Assuming we are dealing with water and air humidity, here we go...

Dry bulb temperature is the usual temperature of the air.

Wet bulb temperature, on the other hand, implies that we have a thermometer whose bulb is soaked with water. The evaporation of water cools the bulb, so the wet bulb temperature may be less than or equal to the dry bulb temperature depending on the rate of evaporation, which depends in turn on air humidity.

Answer 2

It's pretty much just as it sounds. A dry bulb temperature is a temperature reading when the bulb containing the mercury is dry, and a wet bulb reading is when the bulb is surrounded by a thin wet cloth. To take a proper wet bulb reading, the bulb should be swung through the air.
The reason the two are taken is to get an estimate of the air's humidity. If the air had a humidity of 100%, no more water can evaporate into the air. So the wet bulb would not experience any evaporative cooling. The wet bulb temperature and the dry bulb temperature would be almost the same. On the other hand, if the air was very dry, the wet bulb would cool down as water evaporated and you would see a large difference between the wet and dry bulb temps.

Answer 3

The difference is as simple as their meaning, the wet is the temperature taken using a thermocouple saturated with water, the dry is the ambient temperature in a chamber. Having both values one can determine the relative humidity in a chamber. There are tables that correlate dry and wet temps with relative humidity. Typical devices that use these measurements are salt spray fog chamber, humidity chambers.

Answer 4

http://en.wikipedia.org/wiki/Wet-bulb_temperature

Look it up yourself.