Notes On Ozone

924 Words 4 Pages
Exercise 1

The abundance of nitrogen in the standard dry atmospheric composition is 781,000ppmv.
The mass mixing ratio is the volume mixing ratio multiplied by the molecular mass of nitrogen all divided by the molecular mass of air. As the molecular mass of air, 28.8g, is higher than the molecular mass of nitrogen, 28g, the mass mixing ratio would be lower than the volume mixing ratio.

a) m=F/a m=101300/9.8=10,336 An estimate of the total mass of a column of the atmosphere with a base area of 1m2 is 10,336kg.

b) for a 1m2 column at average surface pressure of 985mb: m= 98500/9.8=10,051 kg
Surface area of the Earth:
4π (6370)^2=509,904,363.8
=5.1 x 〖10〗^8 〖km〗^2
=5.1 x 〖10〗^14 m^2

5.1x〖10〗^(14 ) x 10,051=5.13 x 〖10〗^18 kg

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Ozone is produced by the breaking apart of an oxygen molecule by solar UV radiation, a photochemical reaction, to form two oxygen atoms. Three of these oxygen atoms then combine to form ozone, O3. As this reaction is reliant on solar UV radiation, it is greatest in areas with larger amounts of radiation, the tropics. However, the ozone layers are found to be thicker at higher latitudes rather than at the tropics. Meridional and downward transport of ozone molecules in the stratosphere carries the O3 away from the equator and tropics, towards the poles where it collects to form thicker layers. In the northern hemisphere, the greatest column densities occur during spring at the polar latitudes. Therefore, airline passengers flying at high latitudes are exposed to higher ozone concentrations than those flying in the …show more content…
The thickness of the cloud determines whether it is a cold or warm cloud and whether the cloud contains ice crystals. Deep convective clouds, those of thicknesses much greater than 3000ft, lie over the 0o isotherm. Water droplets within the cloud freeze as they pass over the freezing point, and when they fall to the surface due to gravity they partially melt. Upward pressure from rising air then carries the droplet back up through the isotherm causing refreezing. In deeper convective clouds this process can occur many times to form larger ice crystals. Shallow convective clouds in the tropics, with thicknesses lower than 3000ft, do not contain ice crystals. This is because often the cloud does not pass over the 0o isotherm in the atmosphere and so does not reach low enough temperatures. In addition to this, even if the cloud were to be thick enough to lie over the 0o isotherm, it does not necessarily mean the cloud will be able to form ice crystals within it. This is because water droplets in the cloud may not free until temperatures within the cloud are well below the freezing point, sometimes up to -40oC. In the tropics, the surrounding air will be warmer and so a lower freezing point may be required to freeze the water droplets to form

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