What are the main factors that affect the temperature of a place? Expalin in brief

Latitude

• Places near the equator receive direct sunlight and are hotter.

• Places near the poles receive slanting rays and are cooler.

Altitude

• Temperature decreases with height.

• Hill stations are cooler than places in plains.

Distance from the Sea

• Coastal areas have moderate temperatures due to sea breeze.

• Interior areas face extreme heat or cold.

Winds and Air Masses

• Warm winds raise temperature; cold winds lower it.

• Example: Hot winds like loo increase temperature in northern India.

Cloud Cover

• Clouds block sunlight during the day, keeping it cool.

• At night, they trap heat, keeping it warm.

Ocean Currents

• Warm currents raise the temperature of nearby land.

• Cold currents lower the temperature.

Vegetation Cover

• Areas with more trees are cooler.

• Plants release moisture and absorb sunlight, reducing heat.

Define the term Atmospheric Pressure. Explain in brief the Factors that Influence

Atmospheric Pressure

Atmospheric Pressure can be defined as the force per unit area exerted by a column of air on the

Earth’s surface.The factors that influence Atmospheric Pressure are

Altitude

• Atmospheric pressure decreases with height.

• At higher altitudes, the air is thinner and exerts less pressure.

Temperature

• Warm air is lighter and exerts less pressure.

• Cold air is heavier and exerts more pressure.

Water Vapour (Humidity)

• Moist air has less pressure because water vapour is lighter than dry air.

• So, humid areas have lower atmospheric pressure.

Earth’s Rotation

• The rotation of the Earth causes air to move, creating pressure differences.

• This leads to the formation of wind systems.

Gravity

• Gravity pulls air towards the Earth, causing pressure.

• More gravity means more air is held, leading to higher pressure at lower levels.

Season

• In summer, the air becomes warm and rises, causing low pressure areas.

• In winter, the air becomes cold and sinks, causing high pressure areas.

• That’s why seasonal changes lead to shifts in pressure belts and influence winds and

monsoons.

3 What is Weather Forecast? What is its Significance?

• Weather forecast is a prediction of the weather conditions of a particular place for a short

period in the near future.

• It is based on the observation of weather elements and data collected through satellites,

radars, and weather instruments.

The significance of weather forecasting is:

• It helps people plan their day-to-day activities.

• It helps farmers to take decisions related to farming.

• It helps in the smooth operation of transport systems like air, sea, and railways.

• It gives advance warning about natural calamities like storms, floods, and cyclones.

• It helps in disaster preparedness and management.

Deserts have very hot days and equally cold nights.

• Most deserts lie in the subtropical high-pressure belts, where air is dry and skies are

clear.

• This leads to intense heating during the day and rapid cooling at night, resulting in very

hot days and equally cold nights.

2 Atmospheric pressure influences the movement of wind.

• Wind blows from a high-pressure area to a low-pressure area.

• The greater the difference in pressure, the stronger the wind.

IV Find the relative Humidity

If air contains 12 g of water vapour, and can hold a maximum of 20 g at that temperature:

Relative Humidity=(20/12)×100=60%

V Differentiate between

1) Weather & Climate and 2) Isotherms & Isohytes

Weather Climate

1. Condition of the atmosphere over a short

period of time.

1. General weather condition over a

long period of time.

2. Changes day to day. 2. It is permanent in nature.

3. Recorded over a small area. 3. Recorded over a large area.

Isotherms Isohyets

1. Imaginary lines on a map that join

places with the same temperature.

1. Imaginary lines on a map that join

places with the same amount of rainfall.

2. Show the distribution of temperature

across different regions.

2. Show the distribution of rainfall across

different regions.

Example: An isotherm may join all places

having 30°C temperature.

Example: An isohyet may join all places

receiving 100 cm of rainfall.

HW questions

1 How would life be different if weather remained the same every day?(HOTS)

2 What would happen if the Earth stopped rotating? How would it affect weather and

climate?(HOTS)

3 The air at a certain temperature can hold a maximum of 25 grams of water vapour per

cubic metre. If the air actually contains 15 grams of water vapour per cubic metre,

calculate the Relative Humidity.