1. Consider the following statements regarding thunderstorms and tornados:
(1) Both are of short duration, occurring over a small area but are violent.
(2) A thunderstorm is characterised by intense updraft of rising cold air, which causes the clouds to grow bigger and rise to greater height.
(3) The tornado over the sea is called water sprouts.
Which of the statements given above is/are incorrect?
(a) 2 only
(b) 1 and 2 only
(c) 2 and 3 only
(d) 1, 2 and 3
Ans: (a)
Explanation:
Thunderstorms and tornadoes are severe local storms. They are of short duration, occurring over a small area but are violent. Hence statement 1 is correct. Thunderstorms are caused by intense convection on moist hot days. A thunderstorm is a well-grown cumulonimbus cloud producing thunder and lightning. When the clouds extend to heights where sub-zero temperature prevails, hails are formed and they come down as hailstorm. If there is insufficient moisture, a thunderstorm can generate dust storms. A thunderstorm is characterised by intense updraft of rising warm air, which causes the clouds to grow bigger and rise to greater height. This causes precipitation. Later, downdraft brings down to earth the cool air and the rain. Hence statement 2 is incorrect.
From severe thunderstorms sometimes, spiralling wind descends like a trunk of an elephant with great force, with very low pressure at the centre, causing massive destruction on its way. Such a phenomenon is called a tornado. Tornadoes generally occur in middle latitudes. The tornado over the sea is called water sprouts. These violent storms are the manifestation of the atmosphere’s adjustments to varying energy distribution. The potential and heat energies are converted into kinetic energy in these storms and the restless atmosphere again returns to its stable state. Hence statement 3 is correct.
Source: Fundamentals of Physical Geography (NCERT 11th)- chapter 10, Page No.- 91.
2. Consider the following pairs:
Name : Region
1. Cyclones : Indian Ocean
2. Hurricane : Atlantic Ocean
3. Typhoons : Western Australia 4. Willy Willies : Western Pacific, South China Sea
Which of the pairs given above are correctly matched?
(a) 1 and 2 only
(b) 1 and 3 only
(c) 3 and 4 only
(d) 1, 2 and 3
Ans: (a)
Explanation:
Tropical cyclones are violent storms that originate over oceans in tropical areas and move over to the coastal areas bringing about large-scale destruction caused by violent winds, very heavy rainfall and storm surges. This is one of the most devastating natural calamities.
They are known as Cyclones in the Indian Ocean, Hurricanes in the Atlantic, Typhoons in the Western Pacific and South China Sea, and Willy-willies in the Western Australia.
3. Match List-I with List-II and Select the correct answer using the code given below:
List-I : List-II
Type of Cloud : Characteristic
A. Cirrus 1. Layered clouds covering large portion of sky
B. Cumulus 2. Black and Grey Clouds
C. Stratus 3. High altitude clouds which are always white in color
D. Nimbus 4. These clouds look like cotton wool and are present in patches
Codes
A B C D
(a) 3 2 1 4
(b) 1 4 3 2
(c) 1 2 3 4
(d) 3 4 1 2
Ans: (d)
Explanation:
Clouds: Cloud is a mass of minute water droplets or tiny crystals of ice formed by the condensation of the water vapor in free air at considerable elevations. As the clouds are formed at some height over the surface of the earth, they take various shapes. According to their height, expanse, density and transparency or opaqueness clouds are grouped under four types:
Cirrus: Cirrus clouds are formed at high altitudes (8,000 - 12,000m). They are thin and detached clouds having a feathery appearance. They are always white in colour. Cumulus: Cumulus clouds look like cotton wool. They are generally formed at a height of 4,000 -7,000 m. They exist in patches and can be seen scattered here and there. They have a flat base.
Stratus: As their name implies, these are layered clouds covering large portions of the sky. These clouds are generally formed either due to loss of heat or the mixing of air masses with different temperatures.
Nimbus: Nimbus clouds are black or dark grey. They form at middle levels or very near to the surface of the earth. These are extremely dense and opaque to the rays of the sun. Sometimes, the clouds are so low that they seem to touch the ground. Nimbus clouds are shapeless masses of thick vapour.
4. Consider the following statements:
(1) The actual amount of the water vapour present in the atmosphere is known as relative humidity.
(2) The percentage of moisture present in the atmosphere as compared to its full capacity at a given temperature is known as absolute humidity.
(3) Relative humidity and temperature are inversely related to each other.
Which of the statements given above is/are incorrect?
(a) 2 only
(b) 1 and 2 only
(c) 1 and 3 only
(d) 1, 2 and 3
Ans: (b)
Explanation:
Water vapour present in the air is known as humidity. It is expressed quantitatively in different ways.
Absolute humidity: The actual amount of the water vapour present in the atmosphere is known as the absolute humidity. It is the weight of water vapour per unit volume of air and is expressed in terms of grams per cubic metre. The ability of the air to hold water vapour depends entirely on its temperature. The absolute humidity differs from place to place on the surface of the earth.
Relative humidity: The percentage of moisture present in the atmosphere as compared to its full capacity at a given temperature is known as the relative humidity. With the change of air temperature, the capacity to retain moisture increases or decreases and the relative humidity is also affected. It is greater over the oceans and least over the continents.
Relative humidity and temperature are inversely related to each other. Relative humidity falls when the temperature rises. Hence, only statement 3 is correct.
5. Consider the following statements:
(1) Dew is condensation of fine dust particles.
(2) Frost is same as dew but for frost formation, the dew point must be below 0°C.
(3) Fog is moisture deposited in the form of water droplets on cooler surface.
Which of the statements given above is/are correct?
(a) 1 only
(b) 2 only
(c) 1 and 2 only
(d) 1, 2 and 3
Ans: (b)
Explanation:
The transformation of water vapor into water is called condensation. Condensation is influenced by the volume of air, temperature, pressure and humidity. Condensation takes place: (i) when the temperature of the air is reduced to dew point with its volume remaining constant; (ii) when both the volume and the temperature are reduced; (iv) when moisture is added to the air through evaporation. After condensation, the water vapor or the moisture in the atmosphere takes one of the following forms:
Dew
When the moisture is deposited in the form of water droplets on cooler surfaces of solid objects such as stones, grass blades and plant leaves, it is known as dew. The ideal conditions: clear sky, calm air, high relative humidity, and cold and long nights. It is necessary that the dew point is above the freezing point.
Frost
Frost forms on cold surfaces when condensation takes place below freezing point (0°C), i.e. the dew point is at or below the freezing point. The excess moisture is deposited in the form of minute ice crystals instead of water droplets. The ideal conditions: same as those for the formation of dew, except that the air temperature must be at or below the freezing point.
Fog
When the temperature of an air mass containing a large quantity of water vapour falls all of a sudden, condensation takes place within itself on fine dust particles. So, fog is a cloud with its base at or very near to the ground.