Electromagnetic absorption by water

Absorption spectrum (attenuation coefficient vs. wavelength) of liquid water (red), atmospheric water vapor (green) and ice (blue line) between 667 nm and 200 μm. The plot for vapor is a transformation of data Synthetic spectrum for gas mixture Pure H2O (296K, 1 atm) retrieved from Hitran on the Web Information System.
Liquid water absorption spectrum across a wide wavelength range
Part of the pure rotation absorption spectrum of water vapour
Rotating water molecule
Visible light absorption spectrum of pure water (absorption coefficient vs. wavelength)
Dielectric permittivity and dielectric loss of water between 0°C and 100°C, the arrows showing the effect of increasing temperature
Synthetic stick absorption spectrum of a simple gas mixture corresponding to the Earth's atmosphere composition based on HITRAN data created using Hitran on the Web system. Green color - water vapor, WN – wavenumber (caution: lower wavelengths on the right, higher on the left). Water vapor concentration for this gas mixture is 0.4%.

The absorption of electromagnetic radiation by water depends on the state of the water.

- Electromagnetic absorption by water
Absorption spectrum (attenuation coefficient vs. wavelength) of liquid water (red), atmospheric water vapor (green) and ice (blue line) between 667 nm and 200 μm. The plot for vapor is a transformation of data Synthetic spectrum for gas mixture Pure H2O (296K, 1 atm) retrieved from Hitran on the Web Information System.

27 related topics

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Clouds, formed by condensed water vapor

Water vapor

Gaseous phase of water.

Gaseous phase of water.

Clouds, formed by condensed water vapor
frameless
Evidence for increasing amounts of stratospheric water vapor over time in Boulder, Colorado.
MODIS/Terra global mean atmospheric water vapor in atm-cm (centimeters of water in an atmospheric column if it condensed)
Cryogeyser erupting on Jupiter's moon Europa (artist concept)
Artist's illustration of the signatures of water in exoplanet atmospheres detectable by instruments such as the Hubble Space Telescope.

Remote methods such electromagnetic absorption are possible from satellites above planetary atmospheres.

When water is in small quantities (e.g. in a glass) it appears colorless to the human eye.

Color of water

Present.

Present.

When water is in small quantities (e.g. in a glass) it appears colorless to the human eye.
An indoor swimming pool appears blue from above, as light reflecting from the bottom of the pool travels through enough water that its red component is absorbed. The same water in a smaller bucket looks only slightly blue, and observing the water at close range makes it appear colorless to the human eye.
Large bodies of water such as oceans manifest water's inherent blue color.
The hue of the reflected sky contributes to the perceived blue color of water, but much of the blue color comes from light scattering by small particles.
High concentrations of dissolved lime give the water of Havasu Falls a turquoise color.
Glacial rock flour makes New Zealand's Lake Pukaki a lighter turquoise than its neighbors.
Red tide off the California coast

The hue of water is an intrinsic property and is caused by selective absorption and scattering of white light.

South Pole Telescope

10 m diameter telescope located at the Amundsen–Scott South Pole Station, Antarctica.

10 m diameter telescope located at the Amundsen–Scott South Pole Station, Antarctica.

This is particularly important for observing at millimeter wavelengths, where incoming signals can be absorbed by water vapor, and where water vapor emits radiation that can be confused with astronomical signals.

A water molecule consists of two hydrogen atoms and one oxygen atom

Water

Inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a solvent ).

Inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a solvent ).

A water molecule consists of two hydrogen atoms and one oxygen atom
The three common states of matter
Phase diagram of water (simplified)
Tetrahedral structure of water
Model of hydrogen bonds (1) between molecules of water
Water cycle
Overview of photosynthesis (green) and respiration (red)
Water fountain
An environmental science program – a student from Iowa State University sampling water
Total water withdrawals for agricultural, industrial and municipal purposes per capita, measured in cubic metres (m³) per year in 2010
A young girl drinking bottled water
Water availability: the fraction of the population using improved water sources by country
Roadside fresh water outlet from glacier, Nubra
Hazard symbol for non-potable water
Water is used for fighting wildfires.
San Andrés island, Colombia
Water can be used to cook foods such as noodles
Sterile water for injection
Band 5 ALMA receiver is an instrument specifically designed to detect water in the universe.
South polar ice cap of Mars during Martian south summer 2000
An estimate of the proportion of people in developing countries with access to potable water 1970–2000
People come to Inda Abba Hadera spring (Inda Sillasie, Ethiopia) to wash in holy water
Icosahedron as a part of Spinoza monument in Amsterdam.
Water requirement per tonne of food product
Irrigation of field crops
Specific heat capacity of water

Pure water is visibly blue due to absorption of light in the region ca. 600 nm – 800 nm.

This fused quartz sphere was manufactured for use in a gyroscope in the Gravity Probe B experiment. It is one of the most accurate spheres ever manufactured, deviating from a perfect sphere by no more than 40 atoms of thick­ness. Only neutron stars and the single-crystal silicon spheres used in the Avogadro Project are thought to be smoother.

Fused quartz

Glass consisting of almost pure silica in amorphous (non-crystalline) form.

Glass consisting of almost pure silica in amorphous (non-crystalline) form.

This fused quartz sphere was manufactured for use in a gyroscope in the Gravity Probe B experiment. It is one of the most accurate spheres ever manufactured, deviating from a perfect sphere by no more than 40 atoms of thick­ness. Only neutron stars and the single-crystal silicon spheres used in the Avogadro Project are thought to be smoother.
An EPROM with fused quartz window in the top of the package
Phosphorescence in fused quartz from an extremely intense pulse of UV light in a flashtube, centered at 170 nm

However, its infrared transmission is limited by strong water absorptions at 2.2 μm and 2.7 μm.

Calcium-silicate passive fire protection board being clad around steel structure in order to achieve a fire-resistance rating

Calcium silicate

Chemical compound Ca2SiO4, also known as calcium orthosilicate and is sometimes formulated as 2CaO·SiO2.

Chemical compound Ca2SiO4, also known as calcium orthosilicate and is sometimes formulated as 2CaO·SiO2.

Calcium-silicate passive fire protection board being clad around steel structure in order to achieve a fire-resistance rating
Circuit integrity fireproofing of cable trays in Lingen/Ems, Germany using calcium-silicate board system qualified to DIN 4102. Other methods for exterior protection of electrical circuits include boards made of sodium silicate bonded and pressed vermiculite and flexible wraps made of ceramic fibre and rockwool.

It has a low bulk density and high physical water absorption.

John Tyndall

Prominent 19th-century Irish physicist.

Prominent 19th-century Irish physicist.

John Tyndall circa 1850
John Tyndall explored the glacial tributaries feeding Mer de Glace in 1857. General topology (left); dirt-bands in glacier (right).
Tyndall's sensitive ratio spectrophotometer (drawing published in 1861) measured the extent to which infrared radiation was absorbed and emitted by various gases filling its central tube.
Tyndall's setup for preserving broths in optically pure air.
One of Tyndall's setups for showing that sound is reflected in air at the interface between air bodies of different densities.
With this setup Tyndall observed new chemical reactions produced by high frequency light waves acting on certain vapours. The main scientific interest here from his point of view was the additional hard data it lent to the grand question of the mechanism by which molecules absorb radiant energy.
John Tyndall's tutorial books about physics contained many illustrations. This one, from Heat Considered as Mode of Motion, is his setup for demonstrating that air cools during the act of expanding in volume; and that air heats up during the act of compressing in volume. (Click on image for more explanation).
Tyndall caricatured as a preacher in the magazine Vanity Fair, 1872
The Swiss memorial to John Tyndall, with the Aletsch Glacier in the background
Plaques to Tyndall in Leighlinbridge

In radiant-heat experiments that called for much laboratory expertise in the early 1860s, he showed for a variety of readily vaporisable liquids that, molecule for molecule, the vapour form and the liquid form have essentially the same power to absorb radiant heat. (In modern experiments using narrow-band spectra, some small differences are found that Tyndall's equipment was unable to get at; see e.g. absorption spectrum of H2O).

The NOEMA observatory operated by IRAM

Institut de radioastronomie millimétrique

The NOEMA observatory operated by IRAM
NOEMA antennas under the Milky Way
The IRAM 30-meter telescope
The IRAM 30-meter telescope observing by night

Both sites are at high altitude to reduce the absorption by water vapour in Earth's atmosphere.

Opacity of the Earth's atmosphere: the radio window spans larger wavelengths.

Radio window

Range of frequencies of electromagnetic radiation that penetrate the earth's atmosphere.

Range of frequencies of electromagnetic radiation that penetrate the earth's atmosphere.

Opacity of the Earth's atmosphere: the radio window spans larger wavelengths.
The Atacama Large Millimeter Array, an astronomical interferometer of 66 radio telescopes constructed on the 5,000 m (16,000 ft) elevation Chajnantor plateau in Chile.

Tropospheric water vapour greatly affects the upper limit since its resonant absorption frequency bands are 22.3 GHz (λ ≈ 1.32 cm), 183.3 GHz (λ ≈ 1.64 mm) and 323.8 GHz (λ ≈ 0.93 mm).

The structure of

Trihydrogen cation

Cation with formula , consisting of three hydrogen nuclei (protons) sharing two electrons.

Cation with formula , consisting of three hydrogen nuclei (protons) sharing two electrons.

The structure of
The MO diagram of the trihydrogen cation.
A collision of ortho- and para-H2.

Rovibronic spectroscopy is possible with because one of the vibrational modes of, the ν2 asymmetric bend mode (see example of ν2) has a weak transition dipole moment.