Sentences with phrase «low ozone»

Here, a color - coded map showing Earth's north polar region and very low ozone in the stratosphere at an altitude of 12 miles (20 kilometers) in mid-March 2011, the peak of ozone loss.

Ozone measurements from the first week of March already show a region over the North Atlantic with very low ozone levels (< 250 Dobson units, versus minimum values of ~ 300 in the early 1980s).

The absence of a very low ozone profile in the calibration was thus inherently limiting.

Ozone measurements from the first week of March already show a region over the North Atlantic with very low ozone levels (< 250 Dobson units, versus minimum values of ~ 300 in the early 1980s).

Houston, it turned out, had focused on controlling the wrong emissions from the wrong sources to lower its ozone levels, says Daniel Cohan, an associate professor of environmental engineering at Rice University.

The formation of large areas of high pressure in the lower atmosphere both lowers ozone levels, by squeezing the ozone layer above, and may provide the very cold conditions in which ozone destruction is greatest.

Ozone seemed to stunt the trees: Saplings in rural areas, where there was less pollution but more ozone, were smaller than urban trees, which experienced dirtier air and lower ozone levels.

These maps show the state of the ozone hole each year on the day of maximum depth — the day the lowest ozone concentrations were measured.

We've expressed puzzlement that the agency wants to impose more stringent standards when the existing ones are working — lowering ozone levels 18 percent between 2000 and 2013 according to EPA's own data.

Lower ozone levels in the stratosphere may result in more skin cancers, cataracts, and may result in higher incidence of certain diseases.

Not exact matches

Unlike CFCs, pentane does not affect the upper ozone layer, but does contribute to impurities in the lower level of the atmosphere.

Levels of ozone - eating bromine in the lower atmosphere are declining faster than predicted.

City of Dallas Texas Government 334 million green kWh, 40 % of total power used After hosting an eye - opening climate conference, the city government decided to help lower statewide ozone levels by decreasing its conventional power use, says Jill Jordan, an assistant city manager.

Recent evidence now suggests, however, that the molecules can reach the lower edge of the stratosphere, which includes the ozone layer, despite its height 8 kilometers above the poles.

It is possible to do a small - scale test, with quite low risks, that measures key aspects of the risk of geoengineering — in this case the risk of ozone loss.»

Recently, additional ozone production mechanisms have been proposed to resolve the ozone deficit problem, which arises from greater ozone destruction than production in several photochemical models of the upper stratosphere and lower mesosphere.

At present, naturally - emitted VSLS account for around 90 % of the total ozone loss caused by VSLS in the lower stratosphere.

Under the U.S. Clean Air Act, low - level ozone is a listed pollutant.

This is what's known about the dynamics of the stratosphere: Increasing clouds of low - lying ozone, made from the reaction between sunlight and pollution, are showing up in the western U.S. that have little or no industrial activity.

Those gases react with incoming sunlight to produce ozone in the troposphere, the lowest layer of the atmosphere.

The most recent research, which covers 1989 to 1992, and correlates tree sickness with low - level ozone pollution (This Week, 18 June 1994), is due to be published soon.

Earth System Threshold Measure Boundary Current Level Preindustrial Climate Change CO2 Concentration 350 ppm 387 ppm 280 ppm Biodiversity Loss Extinction Rate 10 pm > 100 pm * 0.1 - one pm Nitrogen Cycle N2 Tonnage 35 mmt ** 121 mmt 0 Phosphorous Cycle Level in Ocean 11 mmt 8.5 - 9.5 mmt — 1 mmt Ozone Layer O3 Concentration 276 DU # 283 DU 290 DU Ocean Acidification Aragonite ^ ^ Levels 2.75 2.90 3.44 Freshwater Usage Consumption 4,000 km3 ^ 2,600 km3 415 km3 Land Use Change Cropland Conversion 15 km3 11.7 km3 Low Aerosols Soot Concentration TBD TBD TBD Chemical Pollution TBD TBD TBD TBD * pm = per million ** mmt = millions of metric tons #DU = dobson unit ^ km3 = cubic kilometers ^ ^ Aragonite is a form of calcium carbonate.

The lower stratosphere's ozone continues to decrease, despite the world's success in phasing out ozone - depleting chemicals

Ozone, in turn, forms in the lower atmosphere only if there are sufficient nitrogen oxides there.

If there is hardly any ozone in the lower atmosphere (= troposphere), as is the case in the West Pacific, only little OH can be formed.

Even in the past measurements from the peripheral sections of the now investigated region showed minimal ozone values in the area of the upper troposphere, but not the consistently low values that have now been found across the entire depth of the troposphere.

Although low values at an altitude of around 15 kilometres were known from earlier measurements in the peripheral area of the tropical West Pacific, the complete absence of ozone at all heights was surprising.

Dr West added: «In monetary terms, we found that the benefits for avoided deaths from ozone and PM2.5 were roughly $ 137 per ton CO2 at high valuation, and $ 45 at low valuation, of which 31 % are from foreign GHG reductions.

Senator Tom Carper (DE), top Democrat on the panel, cited an interview in which Hartnett White suggested that low - level ozone, an air pollutant, wasn't harmful unless «you put your mouth over the tailpipe of a car for 8 hours every day.»

They point out that the 50 per cent loss of ozone at low altitudes in the stratosphere is equivalent to a 15 per cent loss of total ozone (Nature, vol 259, p 283).

Similarly, if the level of ozone could be lowered by just 1 part per billion (ppb) nationwide, about 1,900 lives would be saved each year.

Ozone and pollen will simply get worse unless nations pursue aggressive emissions controls and a rapid transition to low - or no - carbon energy systems.

Species such as birch, tulip and linden release very low levels of VOCs, but others such as black gum, poplar, oak and willow produce a lot, leading to ozone levels that can be eight times higher than those linked to the low - impact trees.

A final possibility is that there has been increased formation of the hydroxyl radical in the atmosphere — perhaps caused by the thinning of the ozone layer, which allows more ultraviolet radiation to reach low levels.

«Higher ozone, lower humidity levels associated with dry eye disease.»

The glider will carry instruments to measure levels of aerosols and greenhouse gases, including ozone, methane and water vapour, and will gather information on the exchange of gases and energy between the two lower layers of Earth's atmosphere: the troposphere and the stratosphere.

Detailed analysis of data from the World Meteorological Organization has confirmed record low levels of ozone in the northern hemisphere.

The figure for the column between 12 and 20 kilometres altitude was a record low of 18 Dobson units, representing a loss of 83 per cent of the ozone in that layer.

The region between 45 degrees N and 65 degrees N saw the lowest ever concentrations of total atmospheric ozone over the three continental regions of North America, Europe and Siberia in the winter - spring months of 1992 and 1993.

(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 ozone level was 12 per cent below normal, lower than at any time in the 35 years of continuous monitoring.

The WMO reports the lowest ever measurements of Antarctic stratospheric ozone — 105 Dobson units — from the South Pole a few weeks ago.

Rumen Bojkov, of the UN's World Meteorological Organization, says this might explain the large losses of ozone observed at lower altitudes in the stratosphere.

Air naturally poor in ozone was, for example, lifted into the lower stratosphere above Britain from the sub-tropical Atlantic, by an unusual pattern of atmospheric circulation.

Global warming of the lower atmosphere may encourage the growth of an Arctic «ozone hole».

These show that just such a long - term decrease is taking place, and that there were unusually low values of ozone concentration in 1992 between latitudes 50 degrees North and 60 degrees North, covering Northern Europe, Russia and Canada.

As the satellite orbits the Earth the star appears lower in the horizon, and ozone levels can be measured at any altitude, in 30 - metre slices.

For all three regions, the figures for the past two winter - spring seasons are the lowest ever observed, and statistically well below the mean ozone level in these areas.

And in the lower stratosphere, where the ozone destruction is concentrated, this figure may rise to 60 per cent.

But the researchers, led by AWI atmospheric scientist Markus Rex, found levels in the west Pacific below 10 ozone particles per billion — so low their instruments couldn't even get a precise count.