Why do clouds clear in the sky during a solar eclipse?

A solar eclipse, when the Moon appears between the Sun and the Earth, is always mesmerizing, as it suddenly becomes dark in the middle of the day. However, recent research suggests that an eclipse may cause deeper changes on Earth than just a few moments of darkness. For example, scientists have discovered that at this moment clouds dissipate in the sky. They begin to disappear from the moment the Sun overlaps the Moon by only 15% and continue to do so until the Sun again begins to appear more than 15%. True, this does not apply to all types of clouds, but only to those that are closest to the ground.

Why do clouds dissipate in the sky during a solar eclipse? During a solar eclipse, clouds begin to disappear. Photo.

During a solar eclipse clouds begin to disappear

What clouds disappear during time of solar eclipse

It is very difficult to find out how clouds behave during an eclipse on the surface of the Earth, since eclipses are rare and pass very quickly. The longest eclipse observed by scientists lasted 74 minutes. However, this result was achieved thanks to a flight on a supersonic Concorde aircraft, which literally “chased” the Sun. You can read more about this experiment, carried out in 1974, at the link. In a normal situation, an eclipse lasts less than two minutes.

However, researchers from the Royal Netherlands Meteorological Institute and Delft University of Technology found that small cumulus clouds (those that form bizarre shapes, often resembling various figures) quickly disappear at this moment. Let us remember that in addition to them, there are other types of clouds, for example, cirrus, stratus, lenticular, Kelvin. But all of these types of clouds originate higher in the atmosphere than cumulus.

Which clouds disappear during a solar eclipse. Cumulus clouds often take on bizarre shapes, reminiscent of various figures. Photo.

Cumulus clouds often take on bizarre shapes, resembling various figures

Observations of clouds during a solar eclipse

The layers of clouds are usually quite complex, and they are constantly in motion. Therefore, it is very difficult to obtain the necessary information by observing them during solar eclipses from Earth.

More information can be obtained by observing clouds from satellites, but previously scientists did not take into account the shadow of the Moon during an eclipse when calculating the reflectivity of their upper boundary. As a result, data, including cloud thickness, was inaccurate. To eliminate these inaccuracies, scientists have found a way to correct the influence of the lunar shadow on the surface of clouds at one time or another over a certain area of ​​the Earth.

The authors of the paper then applied their methods to data obtained during three previous solar eclipses over Africa between 2005 and 2016. As a result, they found that the cumulus clouds closest to the ground began to disappear quickly. As mentioned above, this begins to happen at the moment when the Moon covers only 15 percent of the Sun, and continues until the very end of the eclipse. Researchers report this in the journal Communications Earth & Environment.

Observations of clouds during a solar eclipse. During a solar eclipse, the intensity of convection currents decreases. Photo.

During a solar eclipse, the intensity of convection currents decreases

Why do clouds disappear during a solar eclipse

The reason for the disappearance of cumulus clouds, based on satellite data, was not clear. Therefore, the researchers used a computer modeling method. The study showed that when sunlight is blocked, the surface cools, resulting in a decrease in the updraft of warm air from the earth's surface.

It is warm updrafts that contribute to the formation of cumulus clouds, as they carry water vapor, which at high altitudes condenses into droplets that form clouds. Since cumulus clouds cannot replenish moisture during a solar eclipse, they dissipate until updrafts resume. In fact, it is for this reason that cumulus clouds usually disappear in the evening even without any solar eclipse. True, this effect is observed only over land, since the ocean cools down much longer, so a short-term eclipse is not enough for the intensity of the updrafts to significantly decrease. Moreover, over the sea and ocean they can be observed even at night.

As scientists themselves say, observing clouds during an eclipse is important. The fact is that scientists consider an eclipse of the Sun with the help of technological solutions as one of the ways to combat climate warming. Reducing the amount of clouds may partially counteract the intended effect of climate engineering, since clouds reflect sunlight and thus help cool the Earth.

Why do clouds disappear during a solar eclipse. Artificial darkening of the Sun will have negative consequences for the climate. Photo.

Artificial darkening of the Sun will have negative consequences for the climate

In addition , blocking sunlight can have a negative impact on Earth's weather conditions. True, cumulus clouds themselves are not nimbus, that is, they do not cause rain, but they can transform into rain clouds.

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Finally, let us remind you that scientists are also considering other climate engineering technologies that may have less negative consequences. For example, scientists propose fertilizing the ocean. This will allow the ocean to absorb more carbon dioxide from the environment.