Related topics: climate change · earth · climate models · climate · sunlight

Galaxies as 'cosmic cauldrons'

Star formation within interstellar clouds of gas and dust, so-called molecular clouds, proceeds very rapidly yet highly inefficiently. Most of the gas is dispersed by stellar radiation, revealing galaxies to be highly dynamic ...

Tencent profit climbs as it emerges from gaming quagmire

Chinese internet giant Tencent said Wednesday net profit soared nearly 17 percent in the first quarter as the company appeared set to emerge from the battering it received from Beijing's crackdown on gaming.

Location and brand affect people's trust in cloud services

People's stereotypes regarding different locations around the world influence whether they feel secure in storing their data in cloud service centers in those locations, according to researchers at Penn State, who also found ...

Exploring 3-D technology in pottery studies: 'It is the future'

In the depots of the Faculty of Archaeology, many artifacts, accumulated after decades of fieldwork across Europe and the Middle East, are stored. A new project, the Leiden Inventory Depot (LID), aims to unlock this wealth ...

NASA goes infrared on powerful Tropical Cyclone Fani

NASA's Aqua satellite focused an infrared eye on a very powerful Tropical Cyclone Fani as it approached landfall in northeastern India. Fani is a powerful Category 4 hurricane on the Saffir-Simpson Hurricane Wind Scale.

New research takes deeper look at Venus's clouds

Venus is known for its clouds of sulfuric acid covering the entire planet and its super-fast winds moving at hundreds of kilometers per hour, but our neighboring planet's thick clouds make it difficult for scientists to peer ...

page 1 from 23


A cloud is a visible mass of droplets or frozen crystals suspended in the atmosphere above the surface of the Earth or another planetary body. A cloud is also a visible mass attracted by gravity, such as masses of material in space called interstellar clouds and nebulae. Clouds are studied in the nephology or cloud physics branch of meteorology.

On Earth the condensing substance is typically water vapor, which forms small droplets or ice crystals, typically 0.01 mm in diameter. When surrounded by billions of other droplets or crystals they become visible as clouds. Dense deep clouds exhibit a high reflectance (70% to 95%) throughout the visible range of wavelengths. They thus appear white, at least from the top. Cloud droplets tend to scatter light efficiently, so that the intensity of the solar radiation decreases with depth into the gases, hence the gray or even sometimes dark appearance at the base. Thin clouds may appear to have acquired the color of their environment or background and clouds illuminated by non-white light, such as during sunrise or sunset, may appear colored accordingly. In the near-infrared range, clouds look darker because the water that constitutes the cloud droplets strongly absorbs solar radiation at those wavelengths.

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