1. Ozone hole results in
a. More UV radiation reaching the earth
b. Cooling of the earth
c. Warming of the earth
d. Increased incidence of skin cancers
e. Decrease in photosynthetic activity of plants
2. Which of the following are greenhouse gases
a. CH4
b. Co2
c. Co
d. O3
e. H2O
3. Consider the points about Polar vortex which brought havoc in US recently by bringing the temperatures down to record low levels
a. Polar vortex is cold air surrounded by Jet streams at the poles
b. Global warming causes intensifying of polar vortex
c. Polar vortex also leads to ozone depletion
d. Arctic polar vortex is more regular and contained than that of Antarctic one
which of the above statements are true
4. Consider the following statements regarding ozone hole (thinning of ozone layer)
a. Ozone hole is more pronounced over arctic than on Antarctic
b. Ozone hole is more pronounced in summer than in winter
c. It is more pronounced at poles than in any other latitude because of more pollution created by western countries like US and UK
which of the above statements is/are true?
5. Which of the following statements regarding Jet streams is true
a. They are fast flowing winds high in the troposphere
b. They are caused by temperature difference but earths rotation does not play any role, unlike other winds like westerlies and trade winds
c. There are two types of Jet streams, namely polar and subtropical in both the hemispheres
d. Polar jet streams are slower than subtropical jet streams
e. In winter the speed of jet streams si compared to summer
f. Global warming makes the jet streams move faster
1.a,d,e
ReplyDelete2.a,b,d,e
3.b
4.all are false...? Not sure abt C
1. along with a,d and e ozone depletion leads to cooling of the upper troposphere! The source of warmth for the upper troposphere is absorption of UV rays by Ozone. But reduction in ozone (ozone hole) reduces less absorption and so less cooling.
ReplyDelete2. a, b, d,e
3. Polar vortex is an imp concept. In 2012 prelims it was there as one of the options and recently it was in news. So you can expect it in the exam in one way or other. Please read more on this. only a,c are correct. Polar vortex is a mass of cold air contained over the poles by the polar jet stream. The jet streams get weaker with global warming and hence their containing effect also become weaker. When Jet stream becomes weaker, the cold air intrudes the southern regions (i.e north of US and Canada). This intrusion of cold air brings temperatures well below zero (-50!). This is What happened in US recently. It is also the reason for ozone hole in the poles. This what is being asked in 2012. Read about Jet streams also.
4. C is absolutely wrong. It is more pronounced over poles just because of cold temperatures and these cold temperatures are further intensified by polar vortex. Cold temperatures are needed for catalytic dissociation of ozone by CFCs. Antarctic is cooler than arctic (why?) so ozone hole is more pronounced over antarctic than in arctic. By similar argument it is more in winter than in summer.
5. Jet streams are fast moving winds in lower stratosphere. They are caused by temp diff and earth rotation. Their speed depends on the the temperature difference b/w poles and mid latitudes. In winter the temp diff is more so they have high speed. In case of global warming poles get hotter and the temperature diff decreases so also their speed. When the speed of polar jet streams reduces they cant contain polar cold air and hence cold winds in US (as explained above). Polar Jet streams are faster compared to subtropical jet streams because temperature diff b/w two air masses is more in case of polar jet streams (read about the mechanism of formation of Jet streams)
3.