Weather:
Weather report carries information about the temperature, humidity and rainfall during the past 24 hours. It also predicts the weather for the day. Humidity is a measure of the moisture in air.
Notes: 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
Rainfall is measured by an instrument called the rain gauge. It is basically a measuring cylinder with a funnel on top to collect rainwater.
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. The temperature, humidity, and other factors are called the elements of the weather.
The weather is such a complex phenomenon that it can vary over very short periods of time. It can happen sometimes that it is sunny in the morning, but suddenly clouds appear from nowhere and it starts raining heavily. Or, a heavy rain may vanish in a matter of minutes and give way to bright sunshine. Since weather is such a complex phenomenon, it is not easy to predict.
There are special thermometers for measuring maximum and minimum tempratutre, called maximum and minimum thermometers. The maximum temperature of the day occurs generally in the afternoon while the minimum temperature occurs generally in the early morning.
Notes: 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.
Climate:
Meteorologists record the weather every day. The records of the weather have been preserved for the past several decades. These help us to determine the weather pattern at a place. The average weather pattern taken over a long time, say 25 years, is called the climate of the place.
If we find that the temperature at a place is high most of the time, then we say that the climate of that place is hot. If there is also heavy rainfall on most of the days in the same place, then we can say that the climate of that place is hot and wet.
The mean temperature for a given month is found in two steps. First we find the average of the temperatures recorded during the month. Second, we calculate the average of such average temperatures over many years. That gives the mean temperature.
Western region of India, for example Rajasthan, will show that 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. 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.
Climate and Adaptation:
Climate has a profound effect on all living organisms. Animals are adapted to survive in the conditions in which they live. Animals living in very cold and hot climate must possess special features to protect themselves against the extreme cold or heat. Features and habits that help animals to adapt to their surroundings are a result of the process of evolution.
The polar regions are situated near the poles, i.e., north pole and south pole. 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.
Examples of some countries where the tropical rainforests are found are India, Malaysia, Indonesia, Brazil, Republic of Congo, Kenya, Uganda, and Nigeria.
1. The polar regions:
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. Let us see how they are adapted by considering the examples of polar bears and penguins.
A. Polar Bear:
Polar bears have white fur so that they are not easily visible in the snowy white background. It protects them from their predators. It also helps them in catching their prey. To protect them from extreme cold, they have two thick layers of fur.
They also have a layer of fat under their skin. In fact, they are so well-insulated that they have to move slowly and rest often to avoid getting overheated.
Physical activities on warm days necessitate cooling. So, the polar bear goes for swimming. It is a good swimmer. Its paws are wide and large, which help it not only to swim well but also walk with ease in the snow.
While swimming under water, it can close its nostrils and can remain under water for long duration. It has a strong sense of smell so that it can catch its prey for food. We can understand the adaptations of polar bears with the help of the flow chart shown in Fig.
B. Penguin:
Another well-known animal living in the polar regions is the penguin. It is also white and merges well with the white background. It also has a thick skin and a lot of fat to protect it from cold. we may have seen pictures of penguins huddled together. This they do to keep warm.
Like polar bears, penguins are also good swimmers. Their bodies are streamlined and their feet have webs, making them good swimmers.
It is to be noted that while fish can remain under cold water for long, birds must remain warm to survive. They migrate to warmer regions when winter sets in. They come back after the winter is over. India is one of the destinations of many of these birds.
Siberian crane that comes from Siberia to places like Bharatpur in Rajasthan and Sultanpur in Haryana, and some wetlands of north east and some other parts of India
2. The tropical rain forests:
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.
An important feature of this region 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, tigers, elephants, leopards, lizards, snakes, birds and insects.
The climatic conditions in rainforests are highly suitable for supporting an enormous number and a variety of animals. Since the numbers are large, there is intense competition for food and shelter.
Many animals are adapted to living on the trees. Red-eyed frog has developed sticky pads on its feet to help it climb trees on which it lives. To help them live on the trees, monkeys have long tails for grasping branches. Their hands and feet are such that they can easily hold on to the branches
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| Red Eyed Frog |
As there is competition for food, some animals are adapted to get food not easily reachable. A striking example is that of the bird Toucan, which possesses a long, large beak. This helps a toucan to reach the fruits on branches which are otherwise too weak to support its weight.
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| Toucan |
Many tropical animals have sensitive hearing, sharp eyesight, thick skin and a skin colour which helps them to camouflage by blending with the surroundings. This is to protect them from predators. For example, big cats (lions and tigers) have thick skins and sensitive hearing.
The lion-tailed macaque (also called Beard ape) lives in the rainforests of Western Ghats.
- Its most outstanding feature is the silver-white mane, which surrounds the head from the cheeks down to its chin.
- It is a good climber and spends a major part of its life on the tree.
- It feeds mainly on fruits.
- It also eats seeds, young leaves, stems, flowers and buds.
- This beard ape also searches for insects under the bark of the trees. Since it is able to get sufficient food on the trees, it rarely comes down on the ground.
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| Macaque |
Another well-known animal of Indian tropical rain forest is the elephant. It has adapted to the conditions of rain forests in many remarkable ways.
- It uses its trunk as a nose because of which it has a strong sense of smell.
- The trunk is also used by it for picking up food. Moreover, its tusks are modified teeth.
- These can tear the bark of trees that elephant loves to eat. So, the elephant is able to handle the competition for food rather well.
- Large ears of the elephant help it to hear even very soft sounds. They also help the elephant to keep cool in the hot and humid climate of the rain forest.
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