Class 7 Science
The day to day condition of atmosphere at a particular place is called weather. The weather can be comfortable, or can be too hot or cold.
Weather Report: The daily report about weather; usually released by the meteorological department is called weather report. Weather report is often shown along with the news on television.
Elements of Weather: The various elements of weather are: temperature, humidity, rainfall, wind-speed, etc.
- Temperature: Temperature depends upon the duration of sunshine. During the summer season, the duration of the sunshine is longer. Due to this, the temperature is high in summer. The day temperature is minimum in the morning and maximum at noon.
- Humidity: Humidity is the amount of moisture present in air. Humidity is generally measured in percentage. Humidity is generally at the highest level; during the rainy season.
- Rainfall: Amount of rainfall is measured in terms of mm. For this, an apparatus; called rain gauge is used.
- Wind-speed: Speed of wind also affects the condition of weather.
Department of Meteorology: This is a Government Department. The Meteorological Department measures the elements of weather and keeps their record. Meteorologists use data from satellites and analyse the data to forecast about the weather.
Climate is the average weather condition of at least 25 years; in a given geographical part.
The climate of India is said to be hot and humid, because the temperature is usually high and so is the humidity for most parts of the year. The climate of Rajasthan is said to be hot and dry because temperature is very high but humidity is very low. On the other hand, the climate of Kashmir is said to be cold because temperature is low.
Rainforest: Rainforest is found generally near the equator. Places near the equator receive more sunshine and hence more rainfall. This makes the place hot and humid. Temperatures vary from 15⁰C to 40⁰C near the equator. Rainforests are also present in some tropical areas.
Desert: Temperature in desert is generally higher and it receives less or little rain fall. So deserts are hot and dry.
Polar Region: Polar Region is at high latitude and hence do not receive adequate sunshine. Due to this, temperature is very low in the Polar Regions. The Polar Region is covered with snow, because of the low temperature.
Climate and Adaptation:
At several places, such as desert, polar region, etc. climate is very harsh. Many organisms live and thrive at these places, in spite of the harsh climate. Animals and plants; living in such places; develop certain features which help them survive the harsh climate. To develop certain features in order to survive the given climate is called adaptation.
Adaptation in Polar Region:
In Polar Regions, the sun does not set for about six months and it does not appear for another six months of the year. These regions are covered with snow for most part of the years. In winter, temperature may down to -37°C. Hence, the climate of Polar Regions becomes extreme and harsh. In spite of such condition, many animals live at those places, for example: Polar Bear, Penguin, Snow Leopard, etc. These animals show various adaptations which help them in surviving in the harsh climate of the Polar Region.
Polar Bear: Polar bear has two thick layers of fur over its body. In addition to this, they have thick layer of fat under the skin; called blubber. These layers act as insulator and prevent the bear from extreme cold. Because of the white fur, the Polar Bear can easily mix with its snowy background and can hide from its prey and predator. Getting hide with surrounding because of special colour and pattern is known as camouflage.
- Polar bears have wide paws with long curved nails, called claws. This helps them to move on the snow. Polar bears keep on swimming to keep them cool. Wide paws work as a rudder, while swimming. They are very good swimmers.
- Polar bear has a highly developed sense of smell. It helps the Polar bear in finding a fish even from under a thick layer of snow.
- These adaptations help Polar Region to survive in the extreme condition of the Polar Region.