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Relative humidity is the ratio of how much water vapour is in the air to how much water vapour the air could potentially contain at a given temperature. It varies with the temperature of the air: colder air can contain less vapour, and water will tend to condense out of the air more at lower temperatures.
Excess free water or hypotonic water can leave the body in two ways – sensible loss such as osmotic diuresis, sweating, vomiting and diarrhea, and insensible water loss, occurring mainly through the skin and respiratory tract. In humans, dehydration can be caused by a wide range of diseases and states that impair water homeostasis in the body ...
For a constant temperature, the smaller the difference, the more moisture there is, and the higher the relative humidity. In the lower troposphere, more moisture (small dew point depression) results in lower cloud bases and lifted condensation levels (LCL). LCL height is an important factor modulating severe thunderstorms.
The dew point of a given body of air is the temperature to which it must be cooled to become saturated with water vapor. This temperature depends on the pressure and water content of the air. When the air is cooled below the dew point, its moisture capacity is reduced and airborne water vapor will condense to form liquid water known as dew. [1]
The wet-bulb temperature is the lowest temperature that may be achieved by evaporative cooling of a water-wetted, ventilated surface.. By contrast, the dew point is the temperature to which the ambient air must be cooled to reach 100% relative humidity assuming there is no further evaporation into the air; it is the temperature where condensation (dew) and clouds would form.
If the air parcel is lifting further beyond the LCL, water vapor in the air parcel will begin condensing, forming cloud droplets. (In the real atmosphere, it is usually necessary for air to be slightly supersaturated, normally by around 0.5%, before condensation occurs; this translates into about 10 meters or so of additional lifting above the ...
Water migrates from areas of high a w to areas of low a w. For example, if honey (a w ≈ 0.6) is exposed to humid air (a w ≈ 0.7), the honey absorbs water from the air. If salami (a w ≈ 0.87) is exposed to dry air (a w ≈ 0.5), the salami dries out, which could preserve it or spoil it.
Both condensation levels indicate the altitude (or pressure) where relative humidity reaches 100%. However, since the actual condensation level depends on the availability of condensation nuclei, clouds typically do not form until the relative humidity is somewhat above 100%.