"Water Cycle in Nature" Water Changes PPT Courseware

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"Water Cycle in Nature" Water Changes PPT Courseware

Question: What weather phenomena are related to the three-state changes of water in real life?

What state of water do they belong to?

Fog, clouds, rain, dew, frost, snow, hail

How are clouds and fog formed?

Why is there rain and snow?

The cause of fog: At night, because there is no sunlight, the earth dissipates heat quickly. In the morning, the temperature near the ground is relatively low. At this time, if there is more water vapor in the air, it will condense into many small water droplets when it is cold, gather together, and float in the low altitude. This is fog.

Causes of cloud formation: Water vapor enters the atmosphere from the earth's surface and gradually rises to high altitudes. Due to the low atmospheric temperature at high altitudes, the water vapor in the air condenses into small water droplets or small ice crystals, which gather together to form clouds.

Similarities and differences in the causes of clouds and fog

Clouds and fog are similar in that they are both processes in which water vapor liquefies into small water droplets when cooled.

The difference between the formation of clouds and fog: clouds form at high altitudes, and fog forms at low altitudes.

What impact do clouds and fog have on human life?

Clouds: Affect light and form rain, snow and hail. Observe changes in clouds to predict weather.

Fog: affects traffic and human health.

Why does it rain and snow?

What are the characteristics of the weather before it rains? Guess: What does this indicate about the formation of rain?

What phenomenon in life is similar to rain?

Running water on the steamer, tiles or mirror in the bathroom

How would you design an experiment to test your hypothesis? Can you create a "rainfall" phenomenon using the materials below?

What impact do rain and snow have on human life?

Rain is the main source of rivers and lakes. But too much rain can lead to floods, and too little can lead to drought.

Snow has insecticidal and thermal insulation effects on plants, but it affects traffic.

The scientific principle of artificial rainfall: Based on the characteristics of clouds and the principle that rain and snow are formed by condensation of water vapor, aircraft, rockets, etc. are used to spray refrigerant into the clouds in the sky, so that the water vapor in the sky quickly condenses into water droplets. , causing the small water droplets in the clouds to increase and become larger, thus forming rain or snow.

water cycle in nature

Thinking: It rains and snows every year, why can’t all the water in the sky fall?

Discussion: Based on the knowledge of the three-state changes of water and the causes of clouds, fog, rain and snow, think about how water circulates in nature?

Please use simple drawings, simple words and arrows to show how water circulates in nature.

Expand and extend:

1. What are the causes of frost, dew and hail and their impact on human life?

Frost: Water vapor in the air near the ground condenses into small ice crystals that adhere to the ground and plants. Freezing disaster.

Dew: Water vapor in the air near the ground liquefies into small water droplets on plants when cooled. Providing water to plants in water-scarce areas

Hail: Hail is formed by the accumulation of small water droplets and small ice crystals in clouds when they are cold. It often causes mechanical damage and is a disaster.

2. How to survive in the desert? What to do when there is no water?

1. Dig a hole 10cm deep and 30cm in diameter

2. Place a clean plastic cup in the center of the hole

3. Cover the hole with a piece of clean plastic film and secure it with stones.

4. Make a small hole in the center of the film

5. Waiting for water

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Update Time: 2024-11-22

This template belongs to science courseware Hunan Education Edition Fourth Grade Science Volume 1 industry PPT template

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