3rd Class Science Weather, Air and Water Notes - Weather

Weather

1. Weather changes all the time, from day to day and from month to month. Weather depends upon the Sun, clouds, wind and rain.

2. The Sun gives us heat and light which make our days warm. Sun is very hot in the afternoon because the rays fall directly on us. In the mornings and evenings it is not very warm because we get slanting rays from the sun. In the nights, no heat or light comes from the sun. Therefore, days are hot and nights are cool. And also days are hotter in summer but cooler in winter.

3. Cloudy days are cooler than sunny days because clouds obstruct the Sun's rays. Cloudy nights are warmer than the clear nights because clouds do not allow the heat of the Earth to escape.

4. Clouds are classified into four categories. The clouds which look like locks of hair are called cirrus clouds. The puffed-up cottony clouds are called cumulus clouds. The clouds which are like sheets or layers are called stratus clouds. The clouds that give rainy weather are called nimbus clouds.

5. Air currents or flowing air is called wind. When the wind blows very softly, it is called breeze. Strong winds are called storms.

6. Winds also affect the weather. During summer, hot winds called 'loo' make the weather very unpleasant and uncomfortable. During winter cold winds that flow make the days very cold.

7. Some clouds bring us rain. When it rains, the Earth is cooled and plants get water. Farmers need water for their crops. But, too much rains cause floods which damage crops, buildings and human beings.

8. Water evaporates from the lakes, seas and oceans due to sunlight. This water vapour rises above into the atmosphere and cool down to form drops of water. These drops of water come closer to form clouds. When the clouds cool down, it rains. This rain water flows down to ponds, lakes, rivers and finally seas. In this way water flows from oceans to atmosphere to land and finally again to oceans. This is called water cycle.

9. When the weather remains almost the same for a period of time. We call this period a season. We have four seasons in our country. They are summer season, rainy season, winter season and spring season.

10. In summer, days are longer, very warm and dry. Afternoons are very hot and we sweat a lot. We prefer to stay indoors and sit under shady trees. We wear light and cotton clothes in the summer. We drink lots of water, cool drinks and eat ice cream. We eat fruits like water melon, mangoes and litchies.
11. Rainy season is also called monsoon and it comes after summer. Dark clouds fill the sky and bring us rains. When it rains, it becomes very nice and cool. When it does not rain, weather becomes hot and humid and we sweat a lot. When we go out during the rain, we need an umbrella or a raincoat.

12. In winter, the days are shorter and the nights are longer. During winter it becomes very cold and we like to stay indoors. We wear sweaters. Woolen clothes, jerseys, coats and stockings and drink hot milk, tea and coffee.

13. When it is very cold, animals hide in their shelter and some animals go to underground burrows to protect themselves from the cold. During winter we get fruits like apples, oranges, vegetables like cauliflowers, carrot, cabbage and radish.

14. Spring is a very beautiful season with flowers all over. During spring, days and nights are equal. We play outside and go to picnics. We like to watch birds and butterflies in this season.

15. Temperature is the measure of how hot or how cold a day is. It is measured in degrees Celsius of . Maximum temperature is the hottest temperature and minimum is the coldest temperature.

16. During the day land is hotter than the sea. So the air on the land gets warmer than the air above the sea. Hot air, being lighter, rises up and the cool air from the sea takes its place. In this way, the air flows from sea to land. This is called sea breeze.

17. In the night, sea is hotter than the land and cooler air on the land pushes out the hot air over the sea and air starts to blow from the land to sea. This is called land breeze.