Number of Visible Noctilucent Clouds Increasing

Scientists studying the mystery that are night-shining clouds say that more and more people may soon have a chance of seeing one such atmospheric structure in person. The incidence of events involving noctilucent clouds is on the rise, experts add.

In the past, such instances were extremely rare. They occurred at such intervals apart, and in such remote areas, that night-shining cloud researcher Matthew DeLand has only seen them once in person.

The expert has been investigating these peculiar clouds for the better part of 11 years. The formations are also called polar mesospheric clouds, and they are known to develop at very high altitudes.

According to experts, they appear at altitudes of 80 to 85 kilometers, or 50 to 53 miles, and are mostly visible just after a summer sunset, as the sky fades to black. Studies have already shown why.

It would appear that the glowing phenomenon is the result of a combination of factors, including the high altitude of the clouds, and the fact that the Sun still illuminates them, despite having already passed the horizon.

The star's reflect light is what gives the impression that these clouds are shining during the night, as if lit by some hidden natural phenomenon, experts at the NASA Earth Observatory report.

Climate scientists have lately discovered that noctilucent clouds are forming more frequently and becoming brighter than ever before. A team conducted by DeLand arrived at the same conclusion.

The expert is based at the NASA Goddard Space Flight Center (GSFC), in Greenbelt, Maryland, where he holds an appointment as an atmospheric scientist. He also works at Science Systems and Applications Inc.

The researcher and his team used satellite data spanning back to 1978 to discover the clouds, and analyzed information collected by Solar Backscatter Ultraviolet instruments on various spacecraft.

This statistical analysis revealed that the night-shining clouds in the Northern Hemisphere have been exhibiting an increase in brightness throughout the study period.

Additionally, an interesting connection was discovered between the level of solar activity over a certain period and the number of noctilucent clouds that develop over the same time.

DeLand seems to believe that the upward trend in brightness may be linked to subtle atmospheric changes that may have been brought forth by global warming.