KnowledgeBoat Logo
OPEN IN APP

Term 1 — Chapter 3

Weather Instruments

Class 7 - Around the World Geography Solutions


Get Set

Question 1

Read these statements. Then write W and C against the examples of weather and climate respectively.

  1. Some areas of the Sahara Desert do not get rain for many years.
  2. Yesterday the maximum temperature was 44.4°C.
  3. In the past 24 hours, Dibrugarh recorded a rainfall of 13 mm.
  4. In Ladakh, the winter temperature is about -40°C.
  5. Yesterday Kochi experienced variable winds blowing at 2 knots per hour.

Answer

  1. C
  2. W
  3. W
  4. C
  5. W

Quick Quiz

Question 1

What is meteorology?

Answer

The study of weather through careful observation, measurement and recording of the conditions of the various elements of the weather is called meteorology.

Question 2

............... and ............... scales are used to measure temperature.

Answer

Fahrenheit and Celsius scales are used to measure temperature.

Question 3

An aneroid barometer is kept inside a Stevenson screen. True or false?

Answer

False

Corrected statement — The Six's maximum and minimum thermometers are kept inside a Stevenson screen.

Question 4

(Isobars/Isotherms) connect places having equal temperature.

Answer

Isotherms connect places having equal temperature.

Question 5

Name the unit used to measure atmospheric pressure.

Answer

Millibar is the unit used to measure atmospheric pressure.

Fill in the blanks with words from the brackets

Question 1

The ............... (geologists/meteorologists) study weather.

Answer

The meteorologists study weather.

Question 2

............... (Mercury/Nickel) is found inside a thermometer.

Answer

Mercury is found inside a thermometer.

Question 3

An anemometer is used to measure wind ............... (speed/direction).

Answer

An anemometer is used to measure wind speed.

Question 4

The dry bulb thermometer records a temperature ............... (lower/higher) than the wet bulb thermometer.

Answer

The dry bulb thermometer records a temperature higher than the wet bulb thermometer.

Question 5

The ............... (measuring jar/rain gauge) is used to measure the rainwater collected.

Answer

The measuring jar is used to measure the rainwater collected.

Read the clues and write the names

Question 1

The place where weather conditions are recorded

Answer

Weather station

Question 2

The thermometers are kept inside this box

Answer

Stevenson screen

Question 3

An automatic barometer

Answer

Barograph

Question 4

The instrument used to measure humidity

Answer

Hygrometer or wet and dry thermometer

Question 5

Rainfall is measured in this unit

Answer

Millimetres

Give reasons for the following

Question 1

The Six's thermometers are kept inside the Stevenson screen.

Answer

For accurate recording of temperature of free-moving air, the Six's thermometers are kept inside a Stevenson screen which is designed to allow the free movement of air through the box but protects the thermometers from the direct rays of the sun as it can affect the readings of thermometers.

Question 2

The bulb of the wet bulb thermometer is always wrapped in a piece of wet cotton cloth.

Answer

The bulb of the wet bulb thermometer is always wrapped in a piece of wet cotton cloth so that when the wind blows, water from the wet bulb thermometer evaporates and thus lowers the temperature. Hence, the wet bulb thermometer records a temperature lower than the dry bulb thermometer. The difference in the readings of the dry bulb thermometer and wet bulb thermometer helps us to find the humidity in the air. The lesser the difference, the more humid is the air.

Answer these questions

Question 1

How is the Fahrenheit scale different from the Celsius scale? Which one among the two scales is used to measure temperature in India?

Answer

The two most common thermometer scales in use are Fahrenheit and the Celsius scales. On Fahrenheit scale, the melting point of ice is 32°F and the boiling point of water is 212°F whereas on the Celsius scale, the melting and boiling points are 0°C and 100°C respectively. In India, the Celsius scale is used to measure temperature.

Question 2

Describe the working principle of an aneroid barometer.

Answer

An aneroid barometer has a corrugated metal box which is made air tight by pumping air out of it and completely sealed. It has a thin flexible lid which is sensitive to changes of air pressure. The lid is pressed inward or outward as the air pressure increases or decreases respectively. The inward or outward movement of the lid moves a system of levers which is connected to a pointer. The pointer moves over the graduated dial to give the reading of the atmospheric pressure.

Question 3

Name the unit used to measure wind speed. What does the arrow of the wind vane point?

Answer

The unit used to measure wind speed is kilometres or knots per hour.
The arrow of the wind vane points to the direction from which the wind blows.

Question 4

How will you find the humidity in air? What will be your conclusion if both the dry and the wet bulb thermometers show the same reading?

Answer

We can find the humidity in air by using Hygrometer or dry and wet bulb thermometer. It has two identical thermometers fixed on to a wooden frame. The bulb of one thermometer is kept uncovered. This is the dry bulb thermometer. The bulb of other thermometer is wrapped in a piece of wet cotton cloth. This is the wet bulb thermometer.
When the wind blows, water from the wet bulb thermometer evaporates and thus lowers the temperature. Hence, the wet bulb thermometer records a temperature lower than the dry bulb thermometer. The difference in the readings of the dry bulb thermometer and wet bulb thermometer helps us to find the humidity in the air. The lesser the difference, the more humid is the air.

If both the dry and the wet bulb thermometers show the same reading, it can be concluded that the air is fully saturated and the relative humidity is 100 percent.

Question 5

Define isohyets.

Answer

On a map, the distribution of rainfall is shown using lines which join the places having the same amount of rainfall. Such lines are called isohyets. They are labelled with the rainfall values.

PrevNext