Consider the following statements: 1. High clouds primarily reflect solar radiation and cool the surface of the Earth. 2. Low clouds have a high absorption of infrared radiation emanating from the Earth’s surface and thus cause warming effect. Which of the statements given above is/are correct?
- A.1 only
- B.2 only
- C.Both 1 and 2
- D.Neither 1 nor 2
Correct answer
Explanation
The correct answer is D, neither 1 nor 2, because each statement attaches to the wrong kind of cloud. High clouds such as cirrus are thin and made of ice crystals; they let most of the sunlight pass through but absorb the outgoing infrared radiation from the surface, so their net effect is to warm. Low clouds such as stratus and stratocumulus are thick and bright, reflect a large part of the incoming solar radiation back to space and radiate at nearly the temperature of the surface, so their net effect is to cool. Statement 1 gives the cooling role of low cloud to high cloud and statement 2 gives the warming role of high cloud to low cloud, so options A, B and C all fail. The lesson for the heat budget is that cloud height, thickness and composition decide whether a cloud adds to the albedo or to the greenhouse effect.
Read the full article: Insolation, Heat Budget and Temperature: Exam Notes
Practice Questions
View allThe incoming solar radiation that reaches the surface of the earth is known as:
- A.Albedo
- B.Insolation
- C.Terrestrial radiation
- D.Isotherm
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The word is a contraction of incoming solar radiation, and it means the short-wave energy from the sun that reaches the earth, measured in India by the India Meteorological Department in units of energy per unit area per unit time.
Read the full explanation →Out of 100 units of insolation received at the top of the atmosphere, how many units are reflected back to space, a share called the albedo of the earth?
- A.14 units
- B.17 units
- C.35 units
- D.51 units
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Of every hundred units of insolation arriving at the top of the atmosphere, about thirty-five are turned back before they can heat the ground, twenty-seven from the tops of clouds, two from snow and ice covered surfaces and the remainder scattered by the atmosphere; this reflected share is the albedo…
Read the full explanation →The normal lapse rate of temperature in the troposphere is about:
- A.1 °C per 1,000 metres
- B.6.5 °C per 1,000 metres
- C.9.8 °C per 1,000 metres
- D.16 °C per 1,000 metres
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This is the normal lapse rate, the average fall of temperature with height in the troposphere, and it is the reason a hill station is cool while the plain at the same latitude is hot.
Read the full explanation →The earth is nearest to the sun, a position called perihelion, on about which date?
- A.3 January
- B.21 March
- C.21 June
- D.4 July
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The orbit of the earth is an ellipse, so the distance from the sun changes through the year; the earth is closest at perihelion about the third of January and farthest at aphelion about the fourth of July, which is option D and the usual distractor in this question.
Read the full explanation →The horizontal movement of air that transfers heat from one place to another is called:
- A.Conduction
- B.Convection
- C.Advection
- D.Radiation
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Advection is the sideways or horizontal transfer of heat by moving air, and in the middle latitudes most of the day to day variation in temperature comes from it; the hot loo that blows over north India in summer and the cold wave that follows a north-westerly wind in winter…
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