Clouds glow in the night

Astronomers in the northern hemisphere just took the first photos of glowing clouds at night last week. These are clouds that form at the highest position in the atmosphere.

A huge glowing cloud in Sweden in 2008. Photo: worldpress.com.

The clouds glow in the night floating in a position a few kilometers higher than the usual clouds. They fly at least 80 km from the ground. At that height, they glow before dawn and after sunset due to receiving sunlight from the bottom up.

Glowing clouds were seen for the first time in the polar regions of the Earth in 1885. At that time, scientists thought that they were the dust of the Krakatoa volcano in Indonesia (erupted two years earlier). But in the last few years the glowing hordes have appeared at lower latitudes (up to 40 °), and their numbers and sizes have increased. No one has found the cause of that phenomenon, but some scientists think it is an increase in greenhouse gas emissions. According to their argument, exhaust gas makes the top floor of the atmosphere become colder, facilitating the formation of clouds.

Although the number of glowing clouds has increased over the last few decades, their frequency has increased and decreased according to the sun's 11-year operating cycle. They increase sharply when the sun is in the 'gentle' stage, meaning blowing out less UV rays. According to experts, ultraviolet rays can destroy water - which is essential for the process of cloud formation - and maintain high temperatures that prevent ice particles from forming.

Because the sun is in an unusually quiet phase in the last few years, glowing clouds may appear more often in the northern hemisphere this summer with great brightness.

'According to our judgment, the number of glowing clouds appearing in 2009 will reach the highest level ever due to the quiet in the sun's activity,' said Scott Bailey, a leading scientist at US Space Agency (NASA), said.

People who regularly observe the sky in the northern hemisphere will have a good chance to watch the clouds glow in the middle of June through the middle of August. In the southern hemisphere - where there are not so many clouds - people We will easily see them in the next 6 months.