i always thought they were about the same thing
2007-09-24 16:54:01 · 6 answers · asked by cherrihill 5 in Science & Mathematics ➔ Weather
Hi,
dew point is the temperature at which the humidity level becomes 100% -- i.e. the temperature at which precipitation occurs.
humidity level is the percentage of the water in the air relative to how much water it can hold.
the warmer the air, the more water it can hold.
hth.
REgards,
Chas.
2007-09-24 16:59:06 · answer #1 · answered by Chas. 3 · 0⤊ 1⤋
Air is a mixture of gases, one of which is water vapour. Water vapour is constantly condensing into minute water droplets and the droplets are constantly evaporating. The warmer the air, the more evaporation takes place.
For any airmass, there is a temperature at which the rate of evaporation equals the rate of condensation. This temperature is the dew point. At that temperature the relative humidity is 100% and the air is said to be saturated. Were you to measure the air pressure of the water vapour alone in the air, it would give you the saturation vapour pressure for that air.
When the temperature is higher than the dewpoint, the vapour pressure is less than the saturation vapour pressure. The ratio between the vapour pressure and the saturation vapour pressure expressed as a percentage is the relative humidity. The actual amount of water vapour in the air expressed as a percentage of the air or in kilograms per cubic metre is the absolute humidity.
If the air temperature falls below the dewpoint, the rate of condensation exceeds the rate of evaporation and cloud, fog, dew or frost will form depending on where the air is and the temperature.
2007-09-25 00:19:31 · answer #2 · answered by tentofield 7 · 0⤊ 0⤋
They are both measures of the amount of water vapor in the atmosphere, but stated differently. Dew point means the temperature at which the current level of water vapor represents saturation; that is, the temperature at which water will condense out of the air. Surfaces below the dew point will collect dew. If the air temperature drops below the dew point, fog will form.
Humidity level is a more generic term but is often stated as relative humidity. This is the ratio of the partial pressure of water vapor in the air to the saturation pressure at the ambient temperature, expressed as a percentage. RH of 100% indicates that the air temperature is at the dew point.
2007-09-25 00:03:49 · answer #3 · answered by injanier 7 · 0⤊ 0⤋
Dew point is the temperature at which the amount of moisture currently in the air would cause 100% humidity (I.e., dew). Humidity is the amount of moisture in the air, expressed as a percentage of the level of moisture which would constitute total saturation. It is much more difficulat to compare the amount of moisture in the air at two different times given only the the humidity percentage than it is given the dewpoint, since the relative humidity at different temperatures is not directly comparable.
2007-09-25 00:02:46 · answer #4 · answered by PopperDave 3 · 0⤊ 0⤋
The humidity is the percentage of water vapor in the air. If half of the air is water vapor, the humidity is 50%. Humidity will be affected by a change in temperature.
The dew point is the TEMPERATURE at which the water vapor in the air will condense and form dew. It's often somewhere around 50 degrees F.
2007-09-25 00:01:46 · answer #5 · answered by lightcommastix 3 · 0⤊ 2⤋
Dew point represents saturated condition of air for a particular temperature whereas relative humitity indicates how much additional amount of moisture is required(in percentage) to reach saturated condition for that temperature. Hence relative humidity is known as the degree of saturation.
100 percentage of relative humidity represents saturated condition for the particular temperature.
2007-09-25 02:28:33 · answer #6 · answered by Arasan 7 · 0⤊ 0⤋