I need one sentence explanation for true answers. why these answers true ??? Bru
ID: 153314 • Letter: I
Question
I need one sentence explanation for true answers. why these answers true ???
Brutsaert.2.1 Multiple choice. Indicate which of the following statements are correct. An unstable
atmosphere:
Answer : b,d
(a) causes turbulence to be damped;
(b) usually results in a vertical profile of the horizontal wind velocity that is more uniform than that of a stable atmosphere;
(c) causes the mean horizontal wind velocity to be larger (on a regional scale) than that of a neutral atmosphere;
(d) in the surface layer is favorable to disperse the pollutants;
(e) is likely to be found over a deep lake in the spring, when warm air blows over the water;
Brutsaert.2.2
Multiple choice. Indicate which of the following statements are correct. Stable conditions in the atmosphere near the Earth's surface:
Answer : c, d, e
(a) result in increased turbulent mixing (as compared to unstable conditions);
(b) are necessarily the result of smoothness of the surface;
(c) are often observed under nearly windless conditions with surface cooling by long-wave radiation;
(d) would be expected over an extensive and deep-water body in early spring under a cloudy sky, when warm air moves over the water;
(e) are more likely to be accompanied by dew (negative evaporation) than unstable conditions (over land);
(f) indicate that there is a high likelihood for thunderstorm activity.
Explanation / Answer
2.1. An unstable atmosphere in the surface layer is favourable to disperse the pollutants. Unstable atmosphere indicates a variation in weather conditions and more mixing. So the pollution near the ground level gets dispersed. But on the other hand, stable atmosphere means less mixing up of the atmosphere and so larger is the concentration of pollutant near the ground surface. The unstable atmosphere also results in a vertical wind profile of horizontal wind velocity that is more stable than stable atmosphere because in stable atmosphere the warm air goes up and replaces the cold air. Thus, a convection takes place. So, the answer is option b and d.
2.2. Stable atmosphere is more likely to occur when there is a temperature inversion. For example, in the morning, the atmosphere stays stable and dew formation takes place as air near the Earth's surface is cooled up.
Stable atmosphere are often observed under windless condition with surface cooling by long wave radiation because warm air overlies the cold air beneath it. The difference in density helps the cold air to sink.
It also would be expected over an extensive and deep-water body in early spring under a cloudy sky, when warm air moves over the water. The warm air expands and rises up while the denser cool air sinks. So the option is c,d and e.