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How Are Artificial Clouds Formed?

Artificial clouds are being considered as a way to increase cloud cover and bring about cooler temperatures. In nature, clouds are formed by the condensation that occurs when hot, humid air meets cold air. When you exhale on a cold day, the warm air from your lungs combines with cold air to form a tiny cloud. The warm air from jet exhausts leaves behind cloud-like trails when atmospheric conditions are right. Microsoft founder Bill Gates is looking at ways to create clouds on a much larger scale, while others are working on helium-filled cloud canopies to shade outdoor sporting events.

Breath Clouds
- On a cold day, you can see your breath as a visible puff of air, not unlike a cloud. On certain days that puff will stay visible longer than on other days. The warm, humid air you exhale will hang in the air longer if the air itself is also humid. When your warm breath combines with the cooler outside air, condensation will occur if the relative humidity that results reaches 100 percent.
Contrails From Jet Planes
- A contrail is a cloud-like trail created when warm water vapor from a jet's exhaust mixes with cool air. The word "contrail" is a combination of the words "condensation" and "trail." According to the National Weather Service, in areas with a great deal of air traffic, contrails can combine to increase cloud cover as much as 20 percent. The turbulence of the aircraft engines mixes the vapor and air. At high altitudes, very cold temperatures are normal, and at such frigid temperatures very little water is required for condensation. When condensation occurs, the contrail becomes visible.
Seawater Clouds
- Bill Gates, concerned about global warming, has given $4.5 million to researchers at the University of Calgary and the Carnegie Institution for Science. The research Gates is funding is aimed at developing a method whereby ships would suck up large amounts of seawater, then blast that water about a kilometer into the air to create bright white clouds. These clouds would then reflect sunlight back into the atmosphere, possibly resulting in cooler temperatures on Earth. The planned trial involves a 3,800-square-mile area over the Pacific Ocean.
Helium Clouds
- A different kind of artificial cloud is being proposed to cool the stadium for the 2022 World Cup soccer tournament in Qatar. Scientists are planning to build a helium-filled cloud, which would be remotely operated by solar-powered engines. The planned cloud is expected to cost half a million dollars. It would be positioned between the sun and the stadium to shade players and spectators in an area where temperatures higher than 100 degrees are typical.

Nature