advfere.blogg.se - How to get free wii points america

Of this energy, 527 watts is infrared radiation, 445 watts is visible light, and 32 watts is ultraviolet radiation. At zenith, sunlight provides an irradiance of just over 1 kilowatt per square meter at sea level.

Sunlight, at an effective temperature of 5,780 kelvins (5,510 ☌, 9,940 ☏), is composed of near-thermal-spectrum radiation that is slightly more than half infrared. Increasingly, terahertz radiation is counted as part of the microwave band, not infrared, moving the band edge of infrared to 0.1 mm (3 THz). Beyond infrared is the microwave portion of the electromagnetic spectrum. This range of wavelengths corresponds to a frequency range of approximately 430 THz down to 300 GHz. Typically, it is taken to extend from the nominal red edge of the visible spectrum at 700 nanometers (nm) to 1 millimeter (mm). There is no universally accepted definition of the range of infrared radiation.

3.7 Telecommunication bands in the infraredĭefinition and relationship to the electromagnetic spectrum.

1 Definition and relationship to the electromagnetic spectrum.

Non-military uses include thermal efficiency analysis, environmental monitoring, industrial facility inspections, detection of grow-ops, remote temperature sensing, short-range wireless communication, spectroscopy, and weather forecasting. Humans at normal body temperature radiate chiefly at wavelengths around 10 μm (micrometers). Military and civilian applications include target acquisition, surveillance, night vision, homing, and tracking. Infrared thermal-imaging cameras are used to detect heat loss in insulated systems, to observe changing blood flow in the skin, and to detect the overheating of electrical components. Infrared astronomy uses sensor-equipped telescopes to penetrate dusty regions of space such as molecular clouds, to detect objects such as planets, and to view highly red-shifted objects from the early days of the universe. Night-vision devices using active near-infrared illumination allow people or animals to be observed without the observer being detected. Infrared radiation is used in industrial, scientific, military, commercial, and medical applications.

Infrared spectroscopy examines absorption and transmission of photons in the infrared range. It excites vibrational modes in a molecule through a change in the dipole moment, making it a useful frequency range for study of these energy states for molecules of the proper symmetry. Infrared radiation is emitted or absorbed by molecules when changing rotational-vibrational movements. The balance between absorbed and emitted infrared radiation has an important effect on Earth's climate. Slightly more than half of the energy from the Sun was eventually found, through Herschel's studies, to arrive on Earth in the form of infrared. In 1800 the astronomer Sir William Herschel discovered that infrared radiation is a type of invisible radiation in the spectrum lower in energy than red light, by means of its effect on a thermometer. It was long known that fires emit invisible heat in 1681 the pioneering experimenter Edme Mariotte showed that glass, though transparent to sunlight, obstructed radiant heat. As a form of electromagnetic radiation, IR propagates energy and momentum, with properties corresponding to both those of a wave and of a particle, the photon.

Black-body radiation from objects near room temperature is almost all at infrared wavelengths. IR is generally understood to encompass wavelengths from around 1 millimeter (300 GHz) to the nominal red edge of the visible spectrum, around 700 nanometers (430 THz) (although the longer IR wavelengths are often designated rather as terahertz radiation). It is therefore invisible to the human eye. Infrared ( IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. This false-color infrared space telescope image has blue, green and red corresponding to 3.4, 4.6, and 12 μm wavelengths, respectively.