Understanding The Weather Important Question Answer - Class 7 Social Science | Quick Revision Study Guide

Q1: In which layer of the atmosphere does all weather occur?

a) Stratosphere
b) Troposphere
c) Mesosphere
d) Thermosphere
Ans: (b)
Explanation: The Troposphere is the lowest layer of the atmosphere and contains most of the air we breathe, water vapour and the clouds. Because of these features and the large changes in temperature with height near the surface, all common weather phenomena - such as rain, clouds, wind and storms - occur in the Troposphere.

Q2: Which instrument measures temperature?
a) Barometer
b) Thermometer
c) Anemometer
d) Hygrometer
Ans: (b)
Explanation: A thermometer is specially made to measure air temperature. A barometer measures air pressure, an anemometer measures wind speed and a hygrometer measures humidity, so these other instruments are used for different weather elements.

Q3: What does a rain gauge measure?
a) Wind speed
b) Humidity
c) Precipitation
d) Atmospheric pressure
Ans: (c)
Explanation: A rain gauge is used to collect and measure precipitation. It shows how much water has fallen as rain (or melted snow) in a place over a period of time, usually reported in millimetres (for example, 5 mm of rain).

Q4: What unit is used to measure atmospheric pressure?
a) Millimetres
b) Kilometres per hour
c) Millibars
d) Degrees Celsius
Ans: (c)
Explanation: Atmospheric pressure is commonly measured in millibars (mb). A barometer is used to measure this pressure. The other units given measure different things: millimetres often measure rain depth, km/h measures speed, and °C measures temperature.

Q5: Which tool shows the direction of the wind?
a) Wind vane
b) Rain gauge
c) Hygrometer
d) Barometer
Ans: (a)
Explanation: A wind vane points to the direction from which the wind is blowing, so it shows wind direction. A rain gauge measures rainfall, a hygrometer measures humidity and a barometer measures air pressure.

Q6: What is the relative humidity when the air is saturated with water vapor?
a) 0%
b) 50%
c) 100%
d) 20%
Ans: (c)
Explanation: When air is saturated with water vapour it cannot hold any more moisture and the relative humidity reaches 100%. At this level water vapour may start to condense as dew or fog, or form clouds and rain.

Q7: What type of weather station uses sensors without human help?
a) Manual Weather Station
b) Automated Weather Station
c) Portable Weather Station
d) Traditional Weather Station
Ans: (b)
Explanation: An Automated Weather Station (AWS) uses electronic sensors to record temperature, humidity, wind, rainfall and pressure automatically and continuously, without needing a person to take readings. This makes data collection faster and often more reliable than manual observations.

Q8: Which organization in India issues weather warnings?
a) Indian Space Research Organisation
b) Central Pollution Control Board
c) National Disaster Management Authority
d) India Meteorological Department

Ans: (d)

Explanation: The India Meteorological Department (IMD) is the national agency responsible for weather forecasting, issuing warnings for severe weather and providing climate information. It monitors conditions across the country and alerts people and authorities when dangerous weather is expected.

Q9: What natural sign might indicate rain?
a) Birds flying high
b) Ants moving eggs
c) Clear skies
d) Pine cones opening
Ans: (b)
Explanation: When ants move their eggs or carry them to safer, higher places, it often signals that they sense moisture or the ground becoming wet soon. This behaviour is a traditional natural sign indicating that rain may be approaching.

Q10: When was the India Meteorological Department established?
a) 1875
b) 1857
c) 1901
d) 1947

Ans: (a)
Explanation: The India Meteorological Department was established in 1875. Since then it has been central to weather observation, forecasting and issuing warnings to protect life and property across India.

Q11: Define weather and name two elements used to describe it.

Ans: Weather is the condition of the Earth's atmosphere at a particular place and time. Two elements used to describe weather are:
1. Temperature
2. Precipitation.

Q12: What is the troposphere, and why is it important for living things?

Ans: The troposphere is the lowest layer of the atmosphere, closest to Earth's surface, and it is where all usual weather occurs. It is important for living things because it contains most of the air we breathe, includes clouds and rain needed by plants and animals, and maintains temperatures suitable for life.

Q13: How does a rain gauge work, and what does a 5 mm reading mean?

Ans: A rain gauge collects falling rain through a funnel into a graduated cylinder. The depth of water collected is read from the scale on the cylinder. A 5 mm reading means that 5 millimetres of rainwater has fallen over the measured area during the period of collection.

Q14: What is atmospheric pressure, and how does it vary with altitude?

Ans: Atmospheric pressure is the force exerted by the weight of the air above a place. It is higher near sea level, where more air is above, and becomes lower at higher altitudes such as in mountains because there is less air pressing down.

Q15: Define humidity and name the instrument used to measure it.

Ans: Humidity is the amount of water vapour present in the air. It is commonly measured as relative humidity (a percentage) using an instrument called a hygrometer.

Q16: Describe the five main elements of weather and how each is measured.

Ans: The five main elements of weather are:

1. Temperature: How hot or cold the air is, measured with a thermometer in degrees Celsius (°C) or Fahrenheit (°F).

2. Precipitation: Water that falls from the sky (rain, snow, sleet, hail), measured with a rain gauge in millimetres (for example, 5 mm of rainfall).

3. Atmospheric Pressure: The weight of the air pressing down, measured with a barometer in millibars (mb); for example, about 1,013 mb is typical at sea level.

4. Wind: The movement of air, described by direction and speed. Direction is shown by a wind vane and speed by an anemometer, usually given in kilometres per hour (km/h).

5. Humidity: The amount of water vapour in the air, given as relative humidity (0-100%) and measured with a hygrometer.
   These five measurements together give a clear picture of current weather and help forecasters predict what will happen next.

Q17: Explain the role of weather stations and how Automated Weather Stations (AWS) enhance weather monitoring, with examples.

Ans: Weather stations measure different weather elements at a specific location using instruments such as:

• Thermometer - measures temperature
• Rain gauge - measures rainfall
• Barometer - measures air pressure
• Anemometer - measures wind speed
• Hygrometer - measures humidity

These stations take regular readings to track weather patterns and help forecasters predict future conditions.

• Automated Weather Stations (AWS) are advanced systems that use sensors to collect data on temperature, humidity, wind, rainfall, and air pressure without human help. This makes the data more accurate and timely.
• For example, in 2023, an AWS was installed at a glacial lake in Sikkim at over 4,800 metres height. It helps monitor rapid weather and temperature changes and provides early warnings about possible risks such as sudden melting or floods.
• AWS are useful in many areas like agriculture, aviation, navigation and environmental monitoring, because they give continuous, reliable data that improves safety and decision-making, especially in remote or difficult locations.

Q18: Discuss the importance of weather predictions and the role of the India Meteorological Department (IMD) in India.

Ans: Weather predictions are essential because extreme events such as heavy rain, storms, droughts and heat waves are becoming more frequent. Accurate forecasts and warnings help to:

• Warn fishermen about dangerous seas so they can avoid going out
• Evacuate coastal areas before cyclones to save lives
• Help the government prepare disaster resources, which protects lives and property

The India Meteorological Department (IMD), set up in 1875, plays the main role in forecasting weather and issuing alerts. For example, it issued a heat wave and severe weather alert on 19 May 2024 to warn the public and authorities in affected areas.

The IMD uses data from many weather stations, satellites and scientific methods to predict weather. Its forecasts support groups such as:

• Farmers - to plan sowing and harvesting
• Pilots and sailors - for safe travel
• Policymakers - to make informed decisions about public safety and resources

The IMD's motto is "From the sun arises rain," which highlights the sun's role in driving weather patterns and reflects IMD's mission to provide timely forecasts and warnings for the safety and welfare of the country.