Weather, Water and Air - 1 Class 4 Worksheet Science

Q1: Multiple Choice Questions (MCQs).

(i) Which of these does not occur during the water cycle?
(a) Evaporation
(b) Condensation
(c) Pollution
(d) Precipitation
Ans: (c)
There are four main stages in the water cycle. They are evaporation, condensation, precipitation and collection.

(ii) Water vapour condensed to form ice crystals are called
(a) dew
(b) snow
(c) mist
(d) rain
Ans: (d)
Clouds form when the invisible water vapour in the air condenses into visible water droplets or ice crystals.

(iii) Which of the following factors is responsible for weather changes?
(a) Sun
(b) Rotation of earth
(c) Revolution of earth around the sun
(d) All of these
Ans: (d)
Many factors combine to influence weather, the four main ones are solar radiation, the amount of which changes with Earth's tilt, orbital distance from the sun and latitude, temperature, air pressure and the abundance of water.

(iv) What kind of weather is the most uncomfortable?
(a) Hot and humid
(b) Hot and dry
(c) Cool and humid
(d) Cool and dry
Ans: (a)
Water vapour essentially suffocates our skin. On hot and humid days, your skin might feel sticky and overheated, and the air can feel so heavy.

Q2: True or False.

(i) Hot air is heavier than cold air.
Ans: False
Cold air is always heavier than an equal volume of hot air.

(ii) Temperature is higher on mountains.
Ans: False
As air rises, the pressure decreases. It is this lower pressure at higher altitudes that causes the temperature to be colder on top of a mountain than at sea level.

(iii) Weather changes are mainly caused by the heat of the sun.
Ans: True
The energy that the Earth receives from the Sun is the basic cause of our changing weather.

(iv) When clouds are formed close to the ground it is called fog.
Ans: True
Fog is a kind of cloud that touches the ground. Fog forms when the air near the ground cools enough to turn its water vapour into liquid water or ice.

Q3: Name the following.

(a) Water vapour cooling to form water
Ans: Condensation
Condensation is the process by which water vapor in the air is changed into liquid water. As condensation occurs and liquid water forms from the vapor, the water molecules become more organized and heat is released into the atmosphere as a result.

(b) Wind blowing from sea to land
Ans: A sea breeze
A sea breeze describes a wind that blows from the ocean inland towards land.

(c) It forms on plants in cold nights
Ans: Ice crystals
As the air temperature approaches freezing, the surface temperature of plants can dip below freezing, causing ice crystals to form in the same manner that dew forms on warmer nights.

Q4: Fill in the blanks.

(i) The tiny droplets of water present in the air is called ______.
Ans: ice crystals
Water in the gaseous form in the atmosphere is referred to as "water vapor." When water vapor condenses, it can form tiny droplets of liquid water, which are commonly found in clouds or fog. Ice crystals refer to frozen water molecules and are different from liquid water droplets in the atmosphere.

(ii) The processes of evaporation and condensation in the nature results in ______. 
Ans: water cycle
The statement is accurate. The water cycle, also known as the hydrological cycle, involves processes like evaporation (conversion of liquid water to water vapor) and condensation (conversion of water vapor to liquid water), among others, and it is responsible for the continuous circulation of water on Earth.

(iii) The water vapour upon cooling forms ______.
Ans: clouds
Water vapour, when it cools and reaches its dew point, can condense into tiny water droplets or ice crystals, forming clouds. Clouds are essentially collections of these condensed water droplets or ice crystals suspended in the atmosphere.

Q5: Answer the following questions in brief.

(i) What are the factors that affect evaporation in the nature?
Ans: Factors That Affect the Evaporation Temperature: 

• As the temperature increases, the rate of evaporation also increases. 
• Surface area: As the surface area increases, the rate of evaporation increases. 
• Humidity: The rate of evaporation decreases with an increase in humidity.
  

(ii) Define atmosphere.
Ans: “Atmosphere is a protective layer of gases that shelters all life on Earth, keeping temperatures within a relatively small range and blocking out harmful rays of sunlight.” An atmosphere is a blanket of gases that surrounds Earth.

(iii) What is water cycle?
Ans: The water cycle shows the continuous movement of water within the Earth and atmosphere. Liquid water evaporates into water vapor, condenses to form clouds, and precipitates back to earth in the form of rain and snow. Water in different phases moves through the atmosphere (transportation).

Q6: Long answer type questions.

(i) Why does wind blow from the land to the sea during the day?
Ans: During the day time in coastal regions, the air above the land gets heated faster and starts rising. As this hot air rises up, a region of low pressure is created at the surface and air over the sea moves in to this area of low pressure. Hence, the direction of the wind is from the sea to the land during the day.

(ii) Why do you feel very uncomfortable in hot and humid weather?
Ans: Water vapour essentially suffocates our skin. On hot and humid days, your skin might feel sticky and overheated, and the air can feel so heavy that breathing becomes a chore and the less that moisture evaporates from our skin, the more uncomfortably warm we feel.