Physical Geography 3

Question 1

Humidity and how is it expressed, what does it depend upon

Answer 1

Water vapour present in the air is known as humidity. Absolute and relative humidity. Depends upon temperature

Question 2

Absolute humidity

Answer 2

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.

Question 3

Relative humidity

Answer 3

The percentage of moisture present in the atmosphere as compared to its full capacity at a given temperature is known as the relative humidity.

Question 4

Saturation and dew point

Answer 4

The air containing moisture to its full capacity at a given temperature is said to be saturated. It means that the air at the given temperature is incapable of holding any additional amount of moisture at that stage. The temperature at which saturation occurs in a given sample of air is known as dew point.

Question 5

Evaporation and causes

Answer 5

process by which water is transformed from liquid to gaseous state. Heat is the main cause for evaporation.

Question 6

latent heat of vapourisation

Answer 6

The temperature at which the water starts evaporating is referred to as the latent heat of vapourisation.

Question 7

Condensation and causes

Answer 7

The transformation of water vapour into water is called condensation. Condensation is caused by the loss of heat.

Question 8

Sublimation

Answer 8

Change of water from gaseous into solid form, a form of condensation

Question 9

Hygroscopic nuclei

Answer 9

In free air, condensation results from cooling around very small particles termed as hygroscopic condensation nuclei. Particles of dust, smoke and salt from the ocean are particularly good nuclei because they absorb water.

Question 10

The relationship between temperature and humidity

Answer 10

is inversely proportional. The relationship between temperature and humidity is inversely proportional: Warmer air can hold more water vapor than colder air. This means that if the temperature increases, the relative humidity decreases, and the air becomes drier. Colder air has a lower capacity to hold water vapor than warmer air. This means that if the temperature decreases, the relative humidity increases, and the air becomes wetter.

Question 11

What form does water take after condensation in the atmosphere aka types?

Answer 11

dew, frost, fog and clouds.

Question 12

Discuss Dew

Answer 12

When the moisture condenses in the form of water droplets on cooler surfaces of solid objects (rather than nuclei in air above the surface) such as stones, grass blades and plant leaves, it is known as dew. The ideal conditions for its formation are clear sky, calm air, high relative humidity, and cold and long nights. For the formation of dew, it is necessary that the dew point is above the freezing point (0 degree C).

Question 13

Discuss Frost

Answer 13

Frost forms on cold surfaces when condensation takes place below freezing point (0 degree 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 for its formation are clear sky, calm air, high relative humidity, and cold and long nights.

Question 14

Discuss Fog, Mist and Smog

Answer 14

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, the fog is a cloud with its base at or very near to the ground. Mist has more moisture. Smog is when fog is mixed with smoke.

Question 15

Clouds and types

Answer 15

Cloud is a mass of minute water droplets or tiny crystals of ice formed by the condensation of the water vapour in free air at considerable elevations. According to their height, expanse, density and transparency or opaqueness clouds are grouped under four types : (i) cirrus; (ii) cumulus; (iii) stratus; (iv) nimbus.

Question 16

Discuss Cirrus Clouds

Answer 16

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.

Question 17

Discuss Cumulus Clouds

Answer 17

They are generally formed at a height of 4,000 - 7,000 m. Cumulus clouds look like scattered cotton wool with flat base.

Question 18

Discuss Stratus Clouds

Answer 18

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.

Question 19

Discuss Nimbus Clouds

Answer 19

Nimbus clouds are black or dark gray and shapeless. These are extremely dense and opaque to the rays of the sun. They form at middle levels or very near to the surface, almost touching ground.

Question 20

Combo clouds

Answer 20

A combination of these four basic types can give rise to the following types of clouds: 1. high clouds – cirrus, cirrostratus, cirrocumulus; 2. middle clouds – altostratus and altocumulus; 3. low clouds – stratocumulus and nimbostratus and 4. clouds with extensive vertical development – cumulus and cumulonimbus.

Question 21

Precipitation

Answer 21

Release of moisture in free air post condensation. May be liquid aka rainfall, or solid aka snowfall when temp below 0 degrees.

Question 22

​​Sleet

Answer 22

is frozen raindrops and refrozen melted snow-water. When a layer of air with the temperature above freezing point overlies a subfreezing layer near the ground, precipitation takes place in the form of sleet. Raindrops, which leave the warmer air, encounter the colder air below. As a result, they solidify and reach the ground as small pellets of ice not bigger than the raindrops from which they are formed.

Question 23

Hail

Answer 23

Sometimes, drops of rain after being released by the clouds become solidified into small rounded solid pieces of ice and which reach the surface of the earth are called hailstones. These are formed by the rainwater passing through the colder layers. Hailstones have several concentric layers of ice one over the other.

Question 24

Types of Rainfall

Answer 24

On the basis of origin, rainfall may be classified into three main types – the convectional, orographic or relief and the cyclonic or frontal.

Question 25

Convectional Rain

Answer 25

The air on being heated, becomes light and rises up in convection currents. As it rises, it expands and loses heat and consequently, condensation takes place and cumulous clouds are formed. With thunder and lightening, heavy rainfall takes place but this does not last long. Such rain is common in the summer or in the hotter part of the day. It is very common in the equatorial regions and interior parts of the continents, particularly in the northern hemisphere.

Question 26

Orographic/relief Rain and rain shadow area

Answer 26

When the saturated air mass comes across a mountain, it is forced to ascend and as it rises, it expands; the temperature falls, and the moisture is condensed. The chief characteristic of this sort of rain is that the windward slopes receive greater rainfall. After giving rain on the windward side, when these winds reach the other slope, they descend, and their temperature rises. Then their capacity to take in moisture increases and hence, these leeward slopes remain rainless and dry. The area situated on the leeward side, which gets less rainfall is known as the rain-shadow area.

Question 27

Cyclonic Rain

Answer 27

Tropical and extra tropical cyclones

Question 28

regions rainfall is distributed evenly throughout the year

Answer 28

equatorial belt and in the western parts of cool temperate regions.

Question 29

Distribution of rainfall around the world- equator/poles, coast/landmass

Answer 29

In general, as we proceed from the equator towards the poles, rainfall goes on decreasing steadily. The coastal areas of the world receive greater amounts of rainfall than the interior of the continents. The rainfall is more over the oceans than on the landmasses of the world because of being great sources of water. Between the latitudes 35 and 40 N and S of the equator, the rain is heavier on the eastern coasts and goes on decreasing towards the west. But, between 45 and 65 N and S of equator, due to the westerlies, the rainfall is first received on the western margins of the continents and it goes on decreasing towards the east. (due to coriolis induced winds)

Question 30

Classification of climate

Answer 30

Koeppen’s is the most popular based on empirical evidence. Koeppen identified a close relationship between the distribution of vegetation and climate. Classification based on mean annual and mean monthly temperature and precipitation data. He recognised five major climatic groups, four of them are based on temperature and one on precipitation.

Question 31

Group A : Tropical Humid Climates

Answer 31

Location-Tropical humid climates exist between Tropic of Cancer and Tropic of Capricorn. Climate- The sun being overhead throughout the year and the presence of ITCZ make the climate hot and humid.
Temperature/Rainfall- Annual range of temperature is very low and annual rainfall is high.
Three types, namely (i) Af- Tropical wet climate; (ii) Am - Tropical monsoon climate; (iii) Aw- Tropical wet and dry climate.

Question 32

Tropical Wet Climate (Af)

Answer 32

1. Tropical wet climate is found near the equator. The major areas are the Amazon Basin in South America, western equatorial Africa and the islands of East Indies.
2. Significant amount of rainfall occurs in every month of the year as thunder showers in the afternoon.
3. The temperature is uniformly high and the annual range of temperature is negligible. The maximum temperature on any day is around 30°C while the minimum temperature is around 20°C.
4. Tropical evergreen forests with dense canopy cover and large biodiversity are found in this climate.

Question 33

Tropical Monsoon Climate (Am)

Answer 33

1. Tropical monsoon climate (Am) is found over the Indian sub-continent, North Eastern part of South America and Northern Australia.
2. Heavy rainfall occurs mostly in summer. Winter is dry.
3. Deciduous trees are common. Eg Teak, Rosewood.

Question 34

Tropical Wet and Dry Climate (Aw)

Answer 34

1. Occurs at edges of Af climates. Thus north and south of Amazon Basin in South America, western equatorial Africa and the islands of East Indies.
2. The wet season is shorter and the dry season is longer with the drought being more severe.
3. Deciduous forest and tree-shredded grasslands occur in this climate.