Sentences with phrase «polar stratospheric clouds»

Volcanoes don't inject significant chlorine into the stratosphere but they do increase small particles, which increase the amount of polar stratospheric clouds with which the human - made chlorine reacts.

The chemical reactions that break down ozone are particularly intense within cold, acidified clouds called polar stratospheric clouds.

The stable air that causes the ultra-cold conditions where polar stratospheric clouds form in Antarctica is much less likely.

Chlorine eats away at ozone, but only if light is present and if the atmosphere is cold enough to create polar stratospheric clouds on which chlorine chemistry can occur — a relationship that Solomon was first to characterize in 1986.

(Such low air temperatures encourage the formation of icy clouds in the upper atmosphere known as polar stratospheric clouds, which foster the chemical reactions that turn harmless chlorine compounds into ozone eradicators.)

The temperature of the stratosphere is one of the key factors in the springtime depletion of ozone above the Antarctic where in winter it gets colder than anywhere else on Earth, encouraging icy particles to form in polar stratospheric clouds.

That triggered vast polar stratospheric clouds, some of them as big as the continental United States.

«For a period of several weeks, wide areas of the Arctic were covered by polar stratospheric clouds between about 14 and 26 kilometers height.

«We were very much surprised to find polar stratospheric clouds down to heights of about 14 km,» Björn - Martin Sinnhuber says.

Of particular importance are vertically extended polar stratospheric clouds that have been observed to cover wide areas of the Arctic.

There are more polar stratospheric clouds observed now than ever before.

In both the past two winters, researchers saw polar stratospheric clouds over parts of Britain, said Jonathan Shanklin of the British Antarctic Survey.

In the 1980s, Antarctic researchers discovered that these chemical reactions went into overdrive in the super-cold polar stratospheric clouds that formed over the frozen continent.

PSC = polar stratospheric cloud?

Aircraft emissions probably play a crucial role in ozone destruction by fuelling the formation of polar stratospheric clouds.

Unusually low temperatures in the stratosphere, even cold records, are at fault — creating conditions whereby ice crystals form in so called polar stratospheric clouds.

But it does happen whenever temperatures get cold enough for polar stratospheric clouds to form.

Dubbed «mother - of - pearl» clouds because of their attractive appearance, polar stratospheric clouds form at temperatures below -78 ° C.

An eerie «polar stratospheric cloud,» which destroys ozone at a rapid rate, hangs above Kiruna, Sweden, in January 2000.

At the surface of polar stratospheric clouds, chemical reactions take place, converting passive chlorine compounds into reactive compounds that trigger stratospheric ozone depletion.

On the basis of its intended flight route, the Perlan glider might be able to provide the first direct observations of polar stratospheric clouds, a unique type of ice cloud that forms in the polar stratosphere and helps to deplete ozone, Gong adds.

Research: reaction mechanisms and numerical simulation of atmospheric chemistry and transport; photochemistry of ozone and organic trace gases; polar stratospheric clouds and denitrification.

Particles composed of such hydrates are thought to be the principal component of the polar stratospheric clouds that initiate the destruction of ozone.

It normally reaches its widest extent in the southern hemisphere in the spring (August and September), as extreme cold temperatures in the stratosphere facilitate chemical reactions on the surface of polar stratospheric clouds.

We show that chemical loss of column ozone (Î O3) and the volume of Arctic vortex air cold enough to support the existence of polar stratospheric clouds (VPSC) both exceed levels found for any other Arctic winter during the past 40 years.

Subsequently it was shown variation was due to a combination of variation in UV, extremely cold temperatures, formation of polar stratospheric clouds (PSC) and intense atmospheric circulation.

It is caused by chemical reactions that take place primarily on the surface of polar stratospheric clouds, ice particles or liquid droplets which form at high altitudes in extreme cold.

Ozone holes are caused by chemical reactions that take place primarily on the surface of polar stratospheric clouds, ice particles, or liquid droplets, which form at high altitudes in the extreme cold of the polar regions.

But last year, Susan Solomon of MIT — who back in the 1980s became one of the world's most celebrated scientists for uncovering the chemistry of the polar stratospheric clouds — declared that she had detected the first «fingerprints» of the hole closing.

Solomon blamed 2015 on the Calbuco volcano in Chile, which ejected sulphur particles that enhanced the ozone - destroying properties of polar stratospheric clouds.

An unusual persistence of cold temperatures in the stratosphere into March, allowing longer lifetimes for the polar stratospheric clouds that enable conversion of pollutant gases into ozone - destroying chlorine.

The process occurs most readily at temperatures below -77 C, at which point a polar stratospheric cloud can develop (UNEP image below).

Particles composed of such hydrates are thought to be the principal component of the polar stratospheric clouds that initiate the destruction of ozone.