Introduction


The Blanket Effect is intended for others to learn about weather modification and its related subjects in an easy to understand way. Started in 2005, this blog is a work in progress as the technology advances

December 20, 2007

The Pretty (But Deadly) Clouds

(note: article excerpt and all images are from NASA/Ames Research Center)

Polar Stratospheric Clouds and Ozone Depletion

Key Investigators: Owen B. Toon, Azadeh Tabazadeh

Beautiful mother-of-pearl clouds have been observed for centuries at high latitudes over Scandinavia.

(image right of polar stratospheric clouds, as seen over the Arctic in 1989)

The clouds are glimpsed perhaps once a year on those rare winter days when stratospheric temperatures are exceptionally cold.

These clouds were thought to be little more than a colorful curiosity until the 1980s when the Antarctic ozone hole was discovered and satellites showed that polar stratospheric clouds (PSCs) formed much more frequently than observers on the ground had previously thought.

Researchers at NASA Ames were the first to suggest that PSCs were composed of nitric acid particles instead of water ice crystals.

A series of polar expeditions since 1987 has confirmed that the condensation of nitric acid and the adsorption of hydrogen chloride onto the PSC surfaces are critical ingredients in the formation of the ozone hole.

Discovering the conditions controlling which of these compounds occurs in PSCs is essential for evaluating future changes in stratospheric ozone levels.

During the next century the lowering of stratospheric temperatures due to the greenhouse effect and increased concentrations of nitrogen from fleets of high flying supersonic aircraft could modify the frequency of PSC formation, leading to enhanced ozone loss.

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