Why does the dew-point change?

Question

Why does the dew-point not remain constant?

Answer 1

Well everyone hit all around it and they weren't incorrect just not complete. Assuming that you do not know what the dew point means, it means the exact point of temperature at which air reaches 100% humidity. It changes because the air is not always at the same percent of humidity. If the air temperature is 80 degrees and the humidity is 100% then the dew point is 80 degrees. But if the temp is 80 and the humidity is 20% then the dew point is 56 degrees. It would only remain constant if the humidity or air temp remained constant, not likely. It is called relative humidity because cold air cannot hold or contain as much water in a gas form as warmer air can. So as air cools even though the amount of water in a gaseous form remains constant the potential of the air to contain it doesn't.

Answer 2

It all depends on the moisture content in the air. Dew-Point measures the Water Vapor in the atmosphere. Depending on the wind direction and type of weather will determine the dew-point. You would need a parcel bet. 15-25 degree difference from the dew/temp in order to have instability though. Otherwise, the air is either too stable or capped.

Answer 3

dew point is a relative term referring to how much water is in the air

warmer air can hold more water colder of course would hold less.

to the question. if there is no water source around IE say over a desert then the air cannot fill itself with water, but that same air over a ocean would have a tendency to pick up water. there are so many variables involved it is kind of hard to explain it all, but when the dew point reaches the same as the temperature it cannot climb any higher. temperature can never be lower then the dew point. that relationship would be known as relative humidity. so knowing this now if you add in global winds. winds are the largest factor for changing dew points. the water has to come from somewhere so as winds bring in lets say warm air that has been over an ocean it will bring the moisture associated with that air causing changes in local areas. or it could be the exact opposite if say the winds change direction the it may bring in drier air from another region resulting in drops in the dew point.

i hope this helps a bit i am not the best at explain it, but hopefully that helps in some form or another

Answer 4

The dew point temperature is a function of air temperature and relative humidity, but it does not vary as much as the other 2 terms. Weather forecasters tend to use lines of equal dew points (isodrosotherms) to help identify different air masses. There is often a marked changes in dew point temperatures around air mass changes, such as fronts and troughs. In coastal regions, the dew point temperature often rises when there is a sea breeze and lowers when there is an overnight katabatic (land breeze) wind.

Answer 5

the dew point is when temperature drops enough so dew is formed on grass, car windshields, etc. the amount of moisture in air (humidity) and the temp determines dew point