Could Venus have been habitable?

Venus may have been a temperate planet hosting liquid water for 2-3 billion years, until a dramatic transformation starting over 700 million years ago resurfaced around 80% of the planet. A study presented today at the EPSC-DPS ...

Feeling blue: Qatar road turned azure to cool city

Qatar has turned a busy stretch of road in the capital Doha bright blue as part of an experiment to cool the tarmac surface and reduce the temperature of surrounding areas.

Analysis of wildfire smoke will help calibrate climate models

Thunderstorms generated by a group of giant wildfires in 2017 injected a small volcano's worth of aerosol into the stratosphere, creating a smoke plume that lasted for almost nine months. CIRES and NOAA researchers studying ...

First of two Van Allen Probes spacecraft ceases operations

On July 19, 2019, at 1:27 p.m. EDT, mission operators sent a shutdown command to one of two Van Allen Probes spacecraft, known as spacecraft B, from the Johns Hopkins University Applied Physics Lab, or APL, in Laurel, Maryland.

Organic solar cells that last 10 years in space

Scientists from the Skoltech Center for Energy Science and Technology, the Institute for Problems of Chemical Physics of RAS, and the Department of Chemistry of MSU have presented solar cells based on conjugated polymers ...

Carbon-neutral fuel made from sunlight and air

Researchers from ETH Zurich have developed a novel technology that produces liquid hydrocarbon fuels exclusively from sunlight and air. For the first time worldwide they demonstrate the entire thermochemical process chain ...

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Sunlight

Sunlight, in the broad sense, is the total spectrum of the electromagnetic radiation given off by the Sun. On Earth, sunlight is filtered through the atmosphere, and the solar radiation is obvious as daylight when the Sun is above the horizon. Near the poles in summer, the days are longer and the nights are shorter or non-existent. In the winter at the poles the nights are longer and for some periods of time, sunlight may not occur at all. When the direct radiation is not blocked by clouds, it is experienced as sunshine, a combination of bright light and heat. Radiant heat directly produced by the radiation of the sun is different from the increase in atmospheric temperature due to the radiative heating of the atmosphere by the sun's radiation. Sunlight may be recorded using a sunshine recorder, pyranometer or pyrheliometer. Sunlight takes about 8.3 minutes to reach the Earth. The World Meteorological Organization defines sunshine as direct irradiance from the Sun measured on the ground of at least 120 watts per square metre.

Direct sunlight has a luminous efficacy of about 93 lumens per watt of radiant flux, which includes infrared, visible, and ultra-violet light. Bright sunlight provides luminance of approximately 100,000 candela per square meter at the Earth's surface.

Sunlight is a key factor in photosynthesis, a process crucially important for life on Earth.

This text uses material from Wikipedia, licensed under CC BY-SA