ATMOSPHERE AND OCEANS

Atmosphere and Oceans

Atmosphere and Oceans

Paper 1

Doyle, M. and S. Dorling (2002). Visibility trends in the UK 1950-1997, Atmospheric Environment., 36, 3161-3172.

Q1. How does particle size affect visibility?

A1. The size and composition of the particle have profound effect on the visibility due to the fact that particles with wavelength close to0.1µm scatter the light per mass unit in a very efficient manner, which in turn affects the visibility impairment.

Q2. Why do Doyle and Dorling (2002) restrict their analyses to times when the relative humidity is less than 90%?

A2. Doyle and Dorling have limited their analyses to times regardless of the fact that the relative humidity is less than 90%. The rationale behind this is that they were more interested in visibility impairment as a result of emissions and ambient concentrations. Their research is not focused on the degradation of visibility.

Q3. Why do Doyle and Dorling (2002) not consider any data after 1997?

A3. After analysing the time period between 1950 and 2000, Doyle and Dorling identified a significant reduction in the visibility distance after 1997. Human intervention was very irregular post 1997 and automated retrieval of data was also very vague.

Q4. Why is interpolation necessary if the median visibility is to be obtained?

A4. Interpolation is required because of the irregular and extensively dispersed observations that were applied to the visibility data.

Q5. What do Doyle and Dorling (2002) suggest that the step change in visibility around 1973 may be due to?

A5. The step change in visibility around 1973 may be due to the degradation in the visibility which started from 1950 and continued till 2000. Research done in 1974 vindicated that it was worst in 1973 as against all the years in the mentioned era.

Q6. Why have Aldergrove, Tiree and Leuchars not ...