Difference Between Dew Point and Humidity

Dew Point vs Humidity

Both “dew point” and “humidity” are terms used in meteorology, the scientific study of the global atmosphere and weather.

In the simplest sense, both dew point and humidity are two different ways of looking at the same thing which, in this instance, is the amount or quantity of water vapor in the air or, in the broader scope, the atmosphere.

“Dew point” is also known as “dew point temperature” or “vapor density.” It is mostly a measurement of the humidity in the atmosphere expressed as degrees in temperature.
Since the dew point is expressed in degrees (degrees Celsius or Fahrenheit), it is also seen as a temperature or instance where air must be cooled and water vapor must condense to reach saturation. In a sense, it is a saturation temperature or a saturation point.

If water vapor reaches the dew point, there will be a result. The condensed water is called “dew.” If the process happens in a cold environment, the dew point becomes the “frost point” or, more formally, as the “frost point temperature.”

On the other hand, humidity is the amount of water vapor or moisture present in the air or atmosphere. Humidity has three types; absolute humidity, specific humidity, and relative humidity. Relative humidity, in many cases, is often expressed as only “humidity” and is most often associated and compared with the dew point temperature. All forms of humidity are expressed in percentages.

Both the humidity and the dew point have a direct relationship with each other as different methods to measure water vapor. They also share a common relationship with another element, the temperature of air. The dew point as a temperature indicates how much humidity is in the air while the humidity affects the process between the air temperature and the dew point.

If the humidity is high, it means that the range between the atmospheric temperature and the dew point is getting shorter. The direct relationship between the dew point and the humidity means that when the dew point as a temperature goes up, the humidity also goes up. The same applies when one is down; the other is down as well.

Ranges in dew point temperature can actually encompass a wide range of humidity with a certain description of the humidity. For example, a “comfortable” description of the humidity will entail a range of dew point temperatures of 55 to 59 degrees Fahrenheit. While expressed in relative humidity, there is an approximately 31 per cent to 41 per cent humidity in the air. If humidity reaches 100 per cent, the air temperature and dew point temperature will be the same. However, the higher the dew point temperature and relative humidity are, the condition will be extremely uncomfortable for an individual.

The measurements that measure or indicate the dew point are called “dew point meters.” These instruments are often used with and calibrated with other instruments like humidity sensors. On the other hand, psychrometers and hygrometers are used to measure the humidity.

Summary:

1.“Dew point” and “humidity” are relative terms in meteorology. Both have a direct relationship with each other and offer a different view of the water vapor in the atmosphere.
2.Dew point is a temperature and is expressed in degrees Celsius or Fahrenheit. It is primarily a method of measurement of water vapor while humidity is expressed in percentages for the amount of water vapor or moisture present in the atmosphere.
3.The dew point usually refers to condensation while the humidity refers to the saturation of the water vapor.
4.The dew point temperature is the first temperature where condensation begins.
5.The dew point temperature is often associated with relative humidity. They are often used in tandem with humidity descriptions to portray the relationship between each other and to have a more thorough understanding of all concepts.

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