6,000 years ago, the Sahara desert was tropical—what happened?

As little as 6,000 years ago, the vast Sahara Desert was covered in grassland that received plenty of rainfall, but shifts in the world's weather patterns abruptly transformed the vegetated region into some of the driest ...

New technique spots warning signs of extreme events

Many extreme events—from a rogue wave that rises up from calm waters, to an instability inside a gas turbine, to the sudden extinction of a previously hardy wildlife species—seem to occur without warning. It's often impossible ...

Europe's oldest lake traces 1.36 million years of climate

By analysing sediment cores from the bed of Europe's oldest lake, an international team of scientists has created a detailed climate history of the north-central Mediterranean stretching back 1.36 million years—and revealed ...

NASA examines System 99L over Hispaniola in infrared light

When NASA's Aqua satellite passed over the tropical low pressure area known as System 99L it was located over Hispaniola. The AIRS instrument aboard Aqua analyzed the low pressure area in infrared light.

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Rain

Rain is liquid precipitation. On Earth, it is the condensation of atmospheric water vapor into drops heavy enough to fall, often making it to the surface. Rain is the primary source of fresh water for most areas of the world, providing suitable conditions for diverse ecosystems, as well as water for hydroelectric power plants and crop irrigation. However, not all rain reaches the surface; some evaporates while falling through dry air. This is called virga, a phenomenon often seen in hot, dry desert regions. The METAR code for rain is RA.

Rain is also known or suspected on other worlds. On Titan, Saturn's largest moon, infrequent methane rain is thought to carve the moon's numerous surface channels. On Venus, sulfuric acid virga evaporates 25 km from the surface. There is likely to be rain of various compositions in the upper atmospheres of the gas giants, as well as precipitation of liquid neon and helium in the deep atmospheres.

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