NCERT Notes for Class 8 | NCERT Quiz | NCERT Standard 8 - Science

Chapter 7 : Weather, Climate and Adaptation of Animals

Humidity : Humidity is a measure of the moisture in air.

Meteorological Department : The weather reports are prepared by the Meteorological Department of the Government. This department collects data on temperature, wind, etc., and makes the weather prediction.

Rain Gauge : Rainfall is measured by an instrument called the rain gauge. It is basically a measuring cylinder with a funnel on top to collect rainwater.

Temperature : The maximum temperature of the day occurs generally in the afternoon while the minimum temperature occurs generally in the early morning.
Sun : All changes in the weather are caused by the sun. The sun is a huge sphere of hot gases at a very high temperature. The distance of the sun from us is very large. Even then the energy sent out by the sun is so huge that it is the source of all heat and light on the earth.  So, the sun is the primary source of energy that causes changes in the weather. Energy absorbed and reflected by the earth’s surface, oceans and the atmosphere play important roles in determining the weather at any place. 

Weather : The day-to-day condition of the atmosphere at a place with respect to the temperature, humidity, rainfall, wind-speed, etc., is called the weather at that place.

Climate : The average weather pattern taken over a long time, say 25 years, is called the climate of the place.

Tropical region : The tropics (tropical zone or torrid zone) is a region of the Earth surrounding the Equator. It is limited in latitude by the Tropic of Cancer in the northern hemisphere (23.4378°N) and the Tropic of Capricorn in the southern hemisphere (23.4378°S). The tropics include all the areas on the Earth where the Sun reaches a point directly overhead at least once during the solar year. Currently about 40 percent of the world's human population lives within the tropical zone, and by 2060, 60% of the human population will be in the tropics, owing to high birth rates and migration. The tropical region has generally a hot climate because of its location around the equator. Even in the coldest month the temperature is generally higher than
about 15°C. During hot summers, the temperature may cross 40°C. Days and nights are almost equal in length throughout the year. These regions get plenty of rainfall. 

Tropical rainforests : An important feature of tropics is the tropical rainforests. Tropical rainforests are found in Western Ghats and Assam in India, Southeast Asia, Central America and Central Africa. Because of continuous warmth and rain, this region supports wide variety of plants and animals. The major types of animals living in the rainforests are monkeys, apes, gorillas, lions, tigers, elephants, leopards, lizards, snakes, birds and insects. Examples of some countries where the tropical rainforests are found are India, Malaysia, Indonesia, Brazil, Republic of Congo, Kenya, Uganda, and Nigeria. Rainforests cover about 6% of the earth’s surface, but they have more than half of the animal life and about two-thirds of the flowering plants of the planet.

Polar region : The polar regions present an extreme climate. These regions are covered with snow and it is very cold for most part of the year. For six months the sun does not set at the poles while for the other six months the sun does not rise. In winters, the temperature can be as low as –37°C. Animals living there have adapted to these severe conditions. Some well-known countries  that belong to the polar regions are Canada, Greenland, Iceland, Norway, Sweden, Finland, Alaska in U.S.A. and Siberian region of Russia.

Migration : It is a method to escape the harsh, cold conditions.

Siberian crane : Siberian crane is a migrating bird that comes from Siberia to places like Bharatpur in Rajasthan and Sultanpur in Haryana. Some migratory birds travel as much as 15000 km to escape the extreme climatic conditions at home. It  seems that these birds have a built–in sense of direction and know in which direction to travel. Some birds probably use landmarks to guide them. Many birds may be guided by the sun during the day and stars at night. There is some evidence that birds may use the magnetic field of the earth to find direction. 

Climate of western India : In Western region of India, for example Rajasthan, the temperature is high during most part of the year. But during winter,  which lasts only for a few months, the temperature is quite low. This region receives very little rainfall. This is the typical desert climate. It is  hot and dry.

Climate of northeastern India : The northeastern India receives rain for a major part of the year. Therefore, we can say that the climate of the north-east is wet.

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