1. What do you mean by 'weather' and 'climate'? Distinguish between weather and climate?

Ans- Weather means the condition of the atmosphere of a place for a short period of time, like a few hours, a day, or a week. For example, a day could be sunny in the morning and rainy in the afternoon. The weather is temporary and changes frequently.

Climate means the average condition of the atmosphere of a place for a long period of time, at least 30 years. For instance, Assam has a humid climate with regular rainfall during the monsoon season.

Distinguish between Weather and Climate:

1. Time Period

Weather refers to the state of the atmosphere for a short time, like a day or week.

Climate refers to the average atmospheric conditions over a long period, at least 30 years.

2. Area Covered

It affects a small area or place.

It affects a large area or region.

3. Changes

Changes frequently — even within a single day.

Remains more or less constant for many years.

4. Basis of Study

Weather is studied by observing daily or weekly changes.

Climate is studied by observing monthly, seasonal, and yearly data over 30 years.

5. Example

Example: Today’s temperature or rainfall.

Example: Tropical Monsoon Climate of North-East India.

2. Mention the elements of weather and climate. Or/ mention the element of atmosphere?

Ans- The main elements of weather and climate are:

1) Temperature, 2) Pressure, 3) Humidity, 4) Wind, 5) Precipitation.

3. Explain the relationships among temperature, pressure, and humidity.

Ans- There is a close relationship among temperature, pressure, and humidity. When temperature increases, air becomes light, expands, and moves upward, which leads to a decrease in pressure.
Also, warm air can hold more water vapour, so humidity increases with temperature. On the other hand, cold air is heavy, settles down, and creates high pressure, and can hold less moisture, so humidity becomes low.
So, high temperature causes low pressure and high humidity, while low temperature causes high pressure and low humidity.

4. How are the variations in atmospheric pressure caused?

OR/ Explain two reasons why atmospheric pressure varies.

Answer: The variations in atmospheric pressure are primarily caused by two main factors:

a) Air Temperature – When air is warm, it becomes light and creates low pressure. Cold air is heavy and creates high pressure. So, pressure changes with temperature.

b) Surface Elevation – As we go higher from sea level, the air becomes thinner, and pressure decreases. So, pressure is higher in low areas and lower in high areas.

5. Why does the wind blow?

Ans- Wind blows due to the following reason.

1) Wind blows on the Earth's surface in order to maintain a balance in the atmosphere.

2) Wind occurs due to the rotational movement of the Earth. As the Earth rotates on its axis from west to east, the air attains movement and the wind changes its direction.

3) Wind blows because there is a difference in air pressure. Air always moves from a high-pressure area to a low-pressure area, and this movement is called wind.

6. What is precipitation? Name the different types of precipitation. (4/5 marks)

Ans- When the water vapour in the air gets condensed, it becomes heavier and comes down to the earth due to gravity. This is called precipitation. It can be in liquid or solid form like rain, dew, fog, snow, etc.

Different types of precipitation:

1) Rainfall, 2) Drizzle, 3) Snowfall, 4) Fog, 5) Mist, 6) Sleet, 7) Dew.

7. Mention the factors affecting weather and climate. (1/2 marks)

Answer: The factors affecting weather and climate are:

1. Latitude

2. Elevation

3. Nearness to sea

4. Ocean currents

5. Location of hills and mountains

6. Wind

7. Characteristics of land

8. Slope of the land

9. Vegetation

8. Explain with examples the factors of weather and climate. (4/5 marks)

Answer: The following are the factors that affect weather and climate, explained with examples:

1. Latitude:
Sun's rays fall vertically or obliquely at different latitudes. So, temperature is higher at the equator and lower near the poles. That’s why equatorial regions have hot climate, and polar regions have cold climate.

2. Elevation:
Temperature decreases with height. For example, Shillong and Allahabad are at the same latitude, but Shillong is cooler due to higher elevation.

3. Nearness to Sea:
Places near the sea have moderate climate (not too hot or cold), called maritime climate, while interior places have extreme temperatures, called continental climate.

4. Ocean Current:
An ocean current is the flow of ocean water like a river within the sea. Some ocean currents are warm, while some are cold. The warm ocean currents increase the air temperature of nearby coastal areas, while the cold ocean currents decrease it. So, ocean currents control the climate of nearby places.

5. Location of Hills and Mountains:
Moisture-carrying winds strike mountains, causing rainfall on the windward side, but the leeward side remains dry. For example, the southern slopes of the Himalayas get heavy rain, but the Tibetan Plateau remains dry.

6. Wind:
Winds can be warm, cold, moist, or dry. Winds from water bodies carry moisture and bring rain. For example, the south-west monsoon brings heavy rain to Assam and Meghalaya.

7. Characteristics of Land:
Sandy and rocky soils get heated and cooled quickly, causing hot days and cold nights. Forest-covered soils remain wet and cooler.

8. Slope of the Land:
Slopes facing the sun receive more heat. South-facing slopes in the northern hemisphere get more sunlight and are warmer than north-facing slopes.

9. Vegetation:
Forest areas are moist and help with rainfall. Areas without vegetation get less rain and are hotter. Cutting forests reduces rainfall and increases temperature.

9. What are the types of climate? (2 marks)

Ans- The types of climate are: 1) Equatorial climate, 2) Monsoon climate, 3) Savanna climate,

4) Hot desert climate, 5) Temperate desert climate, 6) Mediterranean climate, 7) Temperate humid climate, 8) Temperate grassland climate, 9) Temperate maritime climate, 10) Humid east-coast climate, 11) Sub-Polar (Taiga) climate, 12) Tundra climate.

10. State the various types of climate with a suitable diagram.

The types of climate are given as follows:

1) Equatorial Climate
Hot and humid climate near the equator. Sun’s rays fall vertically. The rainfall is more than 200 cm. Evergreen forests grow. No seasonal change. Conventional rainfall occurs frequently.

2) Monsoon Climate
Found in India, Southeast Asia. Hot and rainy in summer, dry and cold in winter. Summer temperature: 27°C–32°C. Evergreen and deciduous forests grow depending on rainfall.

3) Savanna Climate
Also called the Sudan climate. Found in Central Africa, India, and Brazil. Hot summer, mild winter. Rainfall: 25–40 cm. Tall grasses and bushes grow. Cattle rearing is common.

4) Hot Desert Climate
Found in Sahara, Thar, Kalahari. Very hot summer, cold winter nights. Rainfall below 10 cm. Dusty winds blow. Vegetation includes cactus and thorny bushes due to dryness.

5) Temperate Desert Climate
Found in Gobi, Patagonia, and Iran. Summer temperature: 30–42°C. Winter drops below 0°C. Rainfall is less than 10 cm. Snowfall occurs in winter. The climate is dry and cold.

6) Mediterranean Climate
Found near the Mediterranean Sea, California. Warm, dry summers and cool, wet winters. Average temperature: 10°C–27°C. Suitable for fruits. Vegetation includes evergreen and deciduous trees.

7) Temperate Humid Climate
Also called the Chinese climate. Found in the eastern coastal areas. Summer temperature: 21°C–27°C. Rainfall: 60–100 cm. Winters are cool. Vegetation includes evergreen and deciduous trees.

8) Temperate Grassland Climate
Found in Prairies, Steppes, and Pampas. Hot summer and cold winter. Rainfall: 25–50 cm. Grasslands dominate. Summer temperature: 15°C–20°C. Winter goes below 0°C. Suitable for grazing.

9) Temperate Maritime Climate
Found in west coastal regions. Moderate climate due to ocean. Summer temperature: 15°C–18°C. Winter: 5°C–10°C. Rainfall throughout the year. Known as west coastal climate.

10) Humid East-Coast Climate
Found on east coast between 50°–60° latitudes. Summer temperature: 15°C–20°C. Winter: 6°C–7°C. Rainfall about 100 cm. Some areas get rain year-round, others only in summer.

11) Sub-Polar (Taiga) Climate
Found in Siberia, Canada. Very cold winters, cool summers. Summer temperature: 10°C–30°C. Winter below 0°C. Rainfall: 25–30 cm. Coniferous forests called Taiga grow here.

12) Tundra Climate
Found near Arctic and Antarctic. Very cold. Summer temperature: up to 10°C. Winter below 0°C. Ice covers land for 9 months. Only mosses and lichens grow.

11. Write a short note on the following. (Each 4 marks)

a) Relative humidity.

Relative humidity is the ratio between the amount of water vapour actually present in the air and the amount needed to make the air fully saturated at a certain temperature.

It is always expressed in percentage.

For example, if the air is holding half the water vapour it can hold at a certain temperature, then the relative humidity is 50%.

b) Atmospheric pressure

Atmospheric pressure is the force exerted by air on a unit area. It is highest at sea level and decreases with height. Warm air causes low pressure and cold air causes high pressure. It is measured using a barometer. The average atmospheric pressure at sea level is 1013.2 millibars or 760 mm of mercury.

c) Pressure belts

The air pressure on the Earth is not the same everywhere. Due to the difference in temperature and the rotation of the Earth, some areas have high pressure and some have low pressure. Based on this, the Earth has some permanent pressure belts in both northern and southern hemispheres.

The main pressure belts are:

1. Equatorial Low Pressure Belt

2. Sub-Tropical High Pressure Belt

3. Sub-Polar Low Pressure Belt

4. Polar High Pressure Belt

These belts help in the formation of winds, which blow between high and low-pressure areas.

d) Types of rainfall

Answer: Types of Rainfall

There are five types of rainfall are there.

1. Conventional Rainfall
When the sun heats the Earth’s surface, the air becomes hot and light. This hot air rises upward, and the water vapour in it gets condensed to form clouds and rain.
This is called conventional rainfall.

2. Orographic Rainfall
When moisture-carrying wind hits hills or mountains, it moves upward along the slope and becomes cold. The moisture in the air gets condensed and causes rainfall on the windward side of the mountain. This is called orographic rainfall.

3. Cyclonic Rainfall
When the air in a place becomes very hot, it rises upward and creates a low-pressure centre. Then, air from the surrounding areas blows toward it in a spiral form, creating a cyclone. This cyclone brings heavy rainfall. This is called cyclonic rainfall.

4. Latitudinal Rainfall
This rainfall is caused by permanent winds that blow across oceans and carry moisture. In some latitudes, these winds give rainfall.

5. Forest Rainfall
In forest areas, the air has more moisture due to the respiration of plants. This moist air condenses easily and causes frequent rainfall in forest regions.

e) Effects of latitudes on climate

Ans- The sun's rays fall sometimes vertically and sometimes obliquely at different latitudes. When the rays fall vertically, the temperature increases. But when the rays fall obliquely, the intensity becomes less and so the temperature is also less.

As we move from the equator (0°) towards the poles (90°N and 90°S), the rays become more oblique. So, temperature decreases gradually with the increase of latitude.

f) Effects of vegetation on climate

Ans- Vegetation has a direct effect on climate. Areas with dense forests keep the air around them wet, which helps in causing rainfall. But areas with less or no vegetation get less rain and remain dry. Nowadays, because of cutting trees, many places are getting less rainfall and the temperature is increasing.

g) Monsoon climate

Ans- Monsoon climate is found in India, Bangladesh, Southeast Asia, Southern China, and some other places. It has hot and rainy summers and cold and dry winters. Summer temperature is usually between 27°C to 32°C. Areas with more than 200 cm rainfall grow evergreen trees, and areas with 100–200 cm rainfall have deciduous forests. Places with less rainfall grow grasses and bushes.

h) Taiga types of climates

Ans- Taiga climate is found between 50° and 65° latitudes in the sub-polar regions. It has cool summers with temperatures from 10°C to 30°C and very cold winters, often below 0°C. Some regions get little rainfall in summer and heavy snowfall in winter. Coniferous forests, called Taiga in Siberia, grow widely in this climate.

i) Mediterranean climate

Ans- Mediterranean climate is found on the western coastal regions between 30° and 45° latitudes. It has hot, dry summers (21°C to 27°C) and mild, wet winters (10°C to 13°C). Rainfall mostly occurs in winter. Evergreen and deciduous trees grow here. This climate is also good for horticulture, especially for growing fruits.

j) Savanna climate

Ans- Savanna climate, also called Sudan climate, is found in Central India, Sudan, Argentina, and parts of Africa and Australia. It has hot summers (27°C–28°C) and cool winters (10°C–15°C). Annual rainfall is 25 cm to 40 cm, mostly in late summer. Tall grasses and bushes grow here. Some areas also support agriculture and cattle rearing.

k) Tundra climate

Ans- Tundra climate is found in the regions within the Arctic and Antarctic Circles, such as the northernmost parts of Asia, Canada, and Antarctica. These areas receive very low sunlight for six months, while the other six months remain in darkness. Summer temperature rises only up to 10°C, and winter temperature drops below 0°C. The land stays frozen for nine months, and only lichens and mosses grow in some parts. This region is sparsely populated, with people like the Eskimos and a few nomadic hunters living a very hard life.

l) Mountain climate

Ans- Mountain climate is found in high hills and depends on elevation. As height increases, the climate changes. In the Himalayas, the foothills have equatorial climate, but above 5500 meters, Tundra climate is found. Just below the snow line, Alpine climate occurs with cold air and moderate rainfall. This climate supports grasses, shrubs, coniferous trees, and is good for sheep and cattle rearing.

12. Answer briefly:

(a) How far does the atmosphere extend above the earth's surface?

Ans- The atmosphere roughly extends up to a height of about 10,000 km from the Earth's surface​.

(b) What is the lapse rate?

Ans- Lapse rate is the rate at which temperature decreases by 6.5°C for every 1 km increase in height in the Troposphere.

(c) What is the average atmospheric pressure at sea level?

Ans- The average atmospheric pressure at sea level is 1013.2 millibars (mb)​.

(d) What is the humidity of the air?

Ans- Humidity of air means the amount of water vapour contained in the air.

(e) What is meant by the term 'saturated air'?

Ans- Saturated air is a particular volume of air that holds exactly the amount of water vapour it can retain at a specific temperature condition.

(f) What is the latitudinal extension of the equatorial climate?

Ans- The latitudinal extension of the equatorial climate is between 0° to 10° north and south of the equator.

(g) In which climate is the compos grassland found?

Ans- The Campos grassland is found in the Savanna climate.

(h) Mentioned the latitudinal extension of the temperate desert climate region.

Ans- The latitudinal extension of the temperate desert climate region is between 30° and 40° north and south of the equator.

(i) What is another name for the Chinese climate?

Ans- The other name of the Chinese climate is Temperate Humid Climate.

(j) Give an example of irregular wind.

Ans- Cyclone is an example of irregular wind.

(k) Why does the warm air mass have the capacity to hold more water vapour?

Ans- Warm air can hold more water vapour because its moisture-holding capacity increases with temperature.

(l) Why is there more atmospheric pressure at the lower level of the atmosphere?

Ans- At the lower level, the air is more compressed and dense, so the pressure is higher.

CH-1

WEATHER AND CLIMATE