For the measurement/estimation of which of the following are satellite images/remote sensing data used? 1. Chlorophyll content in the vegetation of a specific location 2. Greenhouse gas emissions from rice paddies of a specific location 3. Land surface temperatures of a specific location Select the correct answer using the code given below.
- A.1 only
- B.2 and 3 only
- C.3 only
- D.1, 2 and 3
Correct answer
Explanation
The correct answer is D, 1, 2 and 3. Satellite sensors are used to estimate all three, because each leaves a signature in the light or heat a place gives off.
Healthy leaves absorb red light and strongly reflect near-infrared light, so satellites estimate chlorophyll and crop health through indices such as NDVI. Thermal infrared sensors, like those on Landsat and India's own satellites, record the heat emitted by the ground and give land surface temperature, which is used for drought, heat-island and crop-stress studies. Flooded rice paddies are a major source of methane; satellites map the flooded area and the crop's stage, and instruments that measure atmospheric methane let scientists estimate emissions from paddies at a given location.
A is wrong: chlorophyll is not the only quantity remote sensing can estimate.
B is wrong: it leaves out chlorophyll, the most common use of all.
C is wrong: it leaves out chlorophyll and paddy emissions.
Exam tip: remote sensing reads reflected light (vegetation, NDVI), emitted heat (surface temperature) and gas absorption (methane, CO2) from space.
Practice Questions
View allStatement I : Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon and the Sun and the rotation of the Earth.
Statement II : The Earth rotates from west to east.
- A.Both the statements are individually true and Statement II is the correct explanation of Statement I
- B.Both the statements are individually true but Statement II is not the correct explanation of Statement I
- C.Statement I is true but Statement II is false
- D.Statement I is false but Statement II is true
Show answer
Both statements are true, but the direction in which the Earth spins does not explain why tides occur. Tides are caused mainly by the Moon's pull, with the Sun adding a smaller pull; the Moon's tide-raising force is roughly twice the Sun's because it is so much closer.
Read the full explanation →Which one of the following states of India has the largest area under dense evergreen forest cover ?
- A.Himachal Pradesh
- B.Arunachal Pradesh
- C.Karnataka
- D.Uttarakhand
Show answer
Its heavy rainfall, warm humid foothills and low population give it the largest stretch of dense evergreen forest among these states.
Read the full explanation →Consider the following statements :
1. Many of the world's largest mountain chains exist beneath the sea.
2. Some mountain chains are revealed as island arcs.
3. The mid-oceanic ridges form the longest mountain chains.
4. The mid-Atlantic ridge rises thirty-three metres above the floor of the Atlantic.
Which of the statements given above are correct ?
- A.1 and 2 only
- B.3 and 4 only
- C.1, 2 and 4 only
- D.1, 2 and 3 only
Show answer
Statement 4 is wrong: the Mid-Atlantic Ridge rises thousands of metres above the ocean floor, not thirty-three metres. The ocean floor has relief as varied as the land.
Read the full explanation →Which one of the following is the main method by which potholes are created in bedrocks by the flowing stream?
- A.Abrasion
- B.Attrition
- C.Corrosion
- D.Solifluction
Show answer
Potholes are drilled into a stream's rocky bed by pebbles and boulders that the swirling water grinds against the rock.
Read the full explanation →Consider the following statements :
1. The Great Northern Plains are formed by basins of three distinct river systems - the Indus, the Ganga and the Brahmaputra.
2. They are one of the most densely populated areas on Earth.
3. Between the Yamuna at Delhi and the Bay of Bengal, nearly 1600 km away, there is a drop of only 200 metres in elevation.
Which of the statements given above are correct?
- A.1, 2 and 3
- B.2 and 3 only
- C.1 and 2 only
- D.1 and 3 only
Show answer
All three statements correctly describe the Northern Plains of India. The Northern Plains were built from alluvium laid down by the Indus, the Ganga and the Brahmaputra and their tributaries, which together drain the Himalayas.
Read the full explanation →