Water vapor

water vapourvaporevaporationgasmoisturewater condensationH 2 OH2Olow-level moisturemoisture in the air
Water vapor, water vapour or aqueous vapor is the gaseous phase of water.wikipedia
609 Related Articles

Properties of water

waterH 2 Owater molecule
Water vapor, water vapour or aqueous vapor is the gaseous phase of water.
It is the most abundant substance on Earth and the only common substance to exist as a solid, liquid, and gas on Earth's surface.

Greenhouse gas

greenhouse gasescarbon emissionsgreenhouse gas emissions
Being a component of Earth's hydrosphere and hydrologic cycle, it is particularly abundant in Earth's atmosphere where it is also a potent greenhouse gas along with other gases such as carbon dioxide and methane.
The primary greenhouse gases in Earth's atmosphere are water vapor (H 2 O), carbon dioxide (CO 2 ), methane (CH 4 ), nitrous oxide (N 2 O), and ozone (O 3 ).

Steam

gaseous gaseous state of waterPC
Use of water vapor, as steam, has been important to humans for cooking and as a major component in energy production and transport systems since the industrial revolution.
Steam is water vapor, which is water in the gas phase.

Ice

water iceicyglacier ice
Water vapor can be produced from the evaporation or boiling of liquid water or from the sublimation of ice.
It may also be deposited directly by water vapor, as happens in the formation of frost.

Atmosphere of Earth

airEarth's atmosphereatmosphere
Being a component of Earth's hydrosphere and hydrologic cycle, it is particularly abundant in Earth's atmosphere where it is also a potent greenhouse gas along with other gases such as carbon dioxide and methane. It is less dense than most of the other constituents of air and triggers convection currents that can lead to clouds.
Air also contains a variable amount of water vapor, on average around 1% at sea level, and 0.4% over the entire atmosphere.

Vapor

vapourfumesvapor phase
Water vapor can be produced from the evaporation or boiling of liquid water or from the sublimation of ice.
In the atmosphere at ordinary temperatures, therefore, gaseous water (known as water vapor) will condense into a liquid if its partial pressure is increased sufficiently.

Sublimation (phase transition)

sublimationsublimessublimate
Water vapor can be produced from the evaporation or boiling of liquid water or from the sublimation of ice.
Similarly the combustion of candles, containing paraffin wax, to carbon dioxide and water vapor is not sublimation but a chemical reaction with oxygen.

Humidity

humidspecific humidityabsolute humidity
Humidity is the amount of water vapor in the air.
Humidity is the concentration of water vapour present in air.

Hygrometer

psychrometersling psychrometerhumidity
The vapor content of air is measured with devices known as hygrometers.
A hygrometer is an instrument used to measure the amount of humidity and water vapour in the atmosphere, in soil, or in confined spaces.

Hydrosphere

waterhydrosphericatmospheric cycling
It is one state of water within the hydrosphere.
The total mass of Earth's hydrosphere is about 1.4 × 10 18 tonnes, which is about 0.023% of Earth's total mass. At any given time, about 20 × 10 12 tonnes of this is in the form of water vapor in the Earth's atmosphere (for practical purposes, 1 cubic meter of water weighs one tonne).

Convection

convectiveconvection currentsconvection current
It is less dense than most of the other constituents of air and triggers convection currents that can lead to clouds. For example, latent heat release in atmospheric convection is directly responsible for powering destructive storms such as tropical cyclones and severe thunderstorms.
It consists of two primary convection cells, the Hadley cell and the polar vortex, with the Hadley cell experiencing stronger convection due to the release of latent heat energy by condensation of water vapor at higher altitudes during cloud formation.

Dew point

dewpointsaturatedsaturation
Water vapour will only condense onto another surface when that surface is cooler than the dew point temperature, or when the water vapour equilibrium in air has been exceeded.
The dew point is the temperature to which air must be cooled to become saturated with water vapor.

Frost

hoar frosthoarfrostfrost-free
Frost and snow are examples of deposition.
Frost is a thin layer of ice on a solid surface, which forms from water vapor in an above freezing atmosphere coming in contact with a solid surface whose temperature is below freezing, and resulting in a phase change from water vapor (a gas) to ice (a solid) as the water vapor reaches the freezing point.

Cloud condensation nuclei

condensation nucleicloud seedCondensation nucleus
In the atmosphere, condensation produces clouds, fog and precipitation (usually only when facilitated by cloud condensation nuclei). Fog and clouds form through condensation around cloud condensation nuclei.
When no CCNs are present, water vapour can be supercooled at about −13°C (8°F) for 5–6 hours before droplets spontaneously form (this is the basis of the cloud chamber for detecting subatomic particles).

Water cycle

hydrological cyclewaterhydrologic cycle
Dew point temperature and relative humidity act as guidelines for the process of water vapor in the water cycle.
In doing so, the water goes through different forms: liquid, solid (ice) and vapor.

Troposphere

troposphericdivergencemid-tropospheric
Approximately 99.13% of it is contained in the troposphere.
It contains 75% of the atmosphere's mass and 99% of the total mass of water vapour and aerosols.

Precipitation

rainfallhydrometeorannual precipitation
In some countries, the evaporation rate far exceeds the precipitation rate. The condensation of water vapor to the liquid or ice phase is responsible for clouds, rain, snow, and other precipitation, all of which count among the most significant elements of what we experience as weather.
In meteorology, precipitation is any product of the condensation of atmospheric water vapour that falls under gravity.

Cloud

cloudscloud formationcloudy
The condensation of water vapor to the liquid or ice phase is responsible for clouds, rain, snow, and other precipitation, all of which count among the most significant elements of what we experience as weather.
On Earth, clouds are formed as a result of saturation of the air when it is cooled to its dew point, or when it gains sufficient moisture (usually in the form of water vapor) from an adjacent source to raise the dew point to the ambient temperature.

Electromagnetic absorption by water

water absorptionabsorptionabsorb
Remote methods such electromagnetic absorption are possible from satellites above planetary atmospheres.
The presence of water vapor in the atmosphere is important for atmospheric chemistry especially as the infrared and near infrared spectra are easy to observe.

Deposition (phase transition)

depositiondepositeddeposits
Deposition is a phase transition separate from condensation which leads to the direct formation of ice from water vapour.
One example of deposition is the process by which, in sub-freezing air, water vapor changes directly to ice without first becoming a liquid.

Exhaled breath condensate

EBC
Forcibly condensing these water droplets from exhaled breath is the basis of exhaled breath condensate, an evolving medical diagnostic test.
It has long been appreciated that the exhaled breath is saturated by water vapour (e.g. by wind musical instrument players), but using it for studies of the lung was probably first described in the Russian scientific literature.

Fog

advection fogfreezing fogground fog
Fog and clouds form through condensation around cloud condensation nuclei.
Fog begins to form when water vapor condenses into tiny liquid water droplets that are suspended in the air.

Thunderstorm

thunderstormssevere thunderstormelectrical storm
For example, latent heat release in atmospheric convection is directly responsible for powering destructive storms such as tropical cyclones and severe thunderstorms.

Volcanic gas

gasgasesgaseous content
However, water vapor is consistently the commonest volcanic gas; as a rule, it comprises more than 60% of total emissions during a subaerial eruption.
The principal components of volcanic gases are water vapor (H 2 O), carbon dioxide (CO 2 ), sulfur either as sulfur dioxide (SO 2 ) (high-temperature volcanic gases) or hydrogen sulfide (H 2 S) (low-temperature volcanic gases), nitrogen, argon, helium, neon, methane, carbon monoxide and hydrogen.

Moisture analysis

moisture analyzers
As this coating absorbs incoming water vapor, an electrical potential is applied to the windings that electrolyzes the water to hydrogen and oxygen.