Humidity is the water (in a gasious state) in the air. dew piont is the air temp when that water condeses and turns back into liquid water.

Humidity is the amount of water vapor in a sample of air compared to the maximum amount of water vapor the air can hold at any specific temperature. Absolute humidity, relative humidity and specific humidity are different ways to express the water content in a parcel of air. Relative humidity is the most frequently used of these expressions because of its importance in weather forecasting. Relative humidity indicates the likelihood of precipitation, dew, or fog. High relative humidity makes people feel hotter outside in the summer because it reduces the effectiveness of sweating to cool the body by preventing the evaporation of perspiration from the skin. This effect is calculated in a heat index table. Warm water vapor has more thermal energy than cool water vapor and therefore more of it evaporates into warm air than into cold air. _______________________ The dew point (or dewpoint) is the temperature to which a given parcel of air must be cooled, at constant barometric pressure, for water vapor to condense into water. The condensed water is called dew. The dew point is a saturation point. When the dew point temperature falls below freezing it is called the frost point, as the water vapor no longer creates dew but instead creates frost or hoarfrost by deposition. The dew point is associated with relative humidity. A high relative humidity indicates that the dew point is closer to the current air temperature. If the relative humidity is 100%, the dew point is equal to the current temperature. Given a constant dew point, an increase in temperature will lead to a decrease in relative humidity. It is for this reason that equatorial climates can have low relative humidity, yet still feel humid. At a given barometric pressure, independent of temperature, the dew point indicates the mole fraction of water vapor in the air, and therefore determines the specific humidity of the air. The dew point is an important statistic for general aviation pilots, as it is used to calculate the likelihood of carburetor icing and fog. http://en.wikipedia.org/wiki/Dew_point http://en.wikipedia.org/wiki/Humidity

once again.... Humidity is the amount of water vapor in a sample of air compared to the maximum amount of water vapor the air can hold at any specific temperature. Absolute humidity, relative humidity and specific humidity are different ways to express the water content in a parcel of air. Relative humidity is the most frequently used of these expressions because of its importance in weather forecasting. Relative humidity indicates the likelihood of precipitation, dew, or fog. High relative humidity makes people feel hotter outside in the summer because it reduces the effectiveness of sweating to cool the body by preventing the evaporation of perspiration from the skin. This effect is calculated in a heat index table. Warm water vapor has more thermal energy than cool water vapor and therefore more of it evaporates into warm air than into cold air. _______________________ The dew point (or dewpoint) is the temperature to which a given parcel of air must be cooled, at constant barometric pressure, for water vapor to condense into water. The condensed water is called dew. The dew point is a saturation point. When the dew point temperature falls below freezing it is called the frost point, as the water vapor no longer creates dew but instead creates frost or hoarfrost by deposition. The dew point is associated with relative humidity. A high relative humidity indicates that the dew point is closer to the current air temperature. If the relative humidity is 100%, the dew point is equal to the current temperature. Given a constant dew point, an increase in temperature will lead to a decrease in relative humidity. It is for this reason that equatorial climates can have low relative humidity, yet still feel humid. At a given barometric pressure, independent of temperature, the dew point indicates the mole fraction of water vapor in the air, and therefore determines the specific humidity of the air. The dew point is an important statistic for general aviation pilots, as it is used to calculate the likelihood of carburetor icing and fog. http://en.wikipedia.org/wiki/Dew_point http://en.wikipedia.org/wiki/Humidity