7. Weather, Climate and Adaptations of Animals to Climate

Do you remember the things that you were asked to pack when you were heading for a hill station? When the sky is cloudy, your parents insist that you carry an umbrella. Have you heard elders in your family discuss the weather before planning a family function? You must have also heard the experts discussing the weather before the start of a game. Have you ever wondered why? The weather may have a profound effect on the game. It has a profound effect on our lives. Many of our daily activities are planned based on the weather predicted for that day. There are daily reports of the weather on the television and radio and in the newspapers. But do you know what this weather really is? 

In this chapter, we will study about the weather and climate. We will also see how different forms of life are adapted to the climate of their habitat.

7.1  Weather

In Fig. 7.1 a sample of weather report from a newspaper is given.

We find that the daily weather report carries information about the temperature, humidity and rainfall during the past 24 hours.  It also predicts the weather for the day. Humidity, as you might know, is a measure of the moisture in air.

Fig. 7.1 A sample of a weather report from a newspaper

Activity 7.1

Cut out the weather reports of the last week from any newspaper. If you do not get a newspaper at home borrow from your neighbours or friends and copy these reports in your notebook. You can also collect weather reports from a library. Paste all the cut-outs on a white sheet or on a chart paper.

Table 7.1. The first row is just a sample. Fill all the columns according to the data in the chart that you have prepared.

Table 7.1
Weather data of a week

*(Rainfall may not be recorded for all the days since it may not rain everyday. Leave the space for rainfall blank if the data is not available.)

Do all the seven days have the same maximum and minimum temperatures, humidity and rainfall? The maximum and minimum temperatures recorded may be the same for some of the days. However, all the parameters are not the same on any two days. Over a week there may be considerable variation. 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 of a place changes day after day and week after week. That is why we often say, “today’s weather is too humid”, or “the weather was warm last week”.

Look at the graph given below which shows the maximum temperature recorded during 03 August 2006 to 09 August 2006 at Shillong, Meghalaya (Fig. 7.2).

As it is clear from any weather report, the maximum and minimum temperatures are recorded every day. Do you know how these temperatures are recorded. In Chapter 4 you have learnt that there are special thermometers for this purpose, called maximum and minimum thermometers. Can you guess when during the day we have the maximum temperature and when the minimum?

The maximum temperature of the day occurs generally in the afternoon while the minimum temperature occurs generally in the early morning.  Can you now understand why in summers we feel so miserable in the afternoon and comparatively comfortable early in the morning? 

What about the times of sunrise and sunset? You know that in winters it becomes dark early and you do not get much time to play. Are the days shorter in winter than in summer?  Try to find it out yourself by completing the project given at the end of the chapter.

7.2 Climate

In Table 7.2 and 7.3, we have given the climatic condition at two places in India. 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. The two places are: Srinagar in Jammu and Kashmir, and Thiruvananthapuram in Kerala.

(Note: The numbers for the mean total rainfall have been rounded off)

By looking at Tables 7.2 and 7.3 we can easily see the difference in the climate of Jammu & Kashmir and Kerala. We can see that Kerala is very hot and wet in comparison to Jammu & Kashmir, which has a moderately hot and wet climate for a part of the year.

7.3 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. Recall from Chapter 9 of your Class VI science book the definition of adaptation. Features and habits that help animals to adapt to their surroundings are a result of the process of evolution.

In Chapter 9 you will learn about the effect of weather and climate on soil. Here we will study the effect of climate on animals only. In Class VI, you have read about adaptations of animals to certain habitats. As examples of adaptation of animals to climatic conditions, we discuss only animals living in polar regions and tropical rainforests.

As the name suggests, 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.

Activity 7.2

Take an outline map of the world. Mark the polar regions in blue. Similarly, mark the tropical regions in red.

(i) 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.

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 durations. 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. 7.3.

Fig. 7.3 Adaptations of polar bear

Another well-known animal living in the polar regions is the penguin
(Fig. 7.4). 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. You may have seen pictures of penguins huddled together. This they do to keep warm. Recall how warm you feel when you are in a hall full of people. Like polar bears, penguins are also good swimmers. Their bodies are streamlined and their feet have webs, making them good swimmers (Fig. 7.5).

Fig. 7.4 Penguins huddled together

Fig. 7.5 Feet of penguin

Other animals living in the polar regions are many types of fishes, musk oxen, reindeers, foxes, seals, whales, and birds.  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. You know probably that India is one of the destinations of many of these birds. You must have seen or heard about the 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 (Fig. 7.6). 

Fig. 7.6 Migratory birds in their habitat/ Migratory birds in flight

(ii) The tropical rainforests

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.

Let us read about the adaptations of these animals to a hot, humid climate.

Fig. 7.7 Red-eyed frog

Fig. 7.8 A new world monkey

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 (Fig. 7.9), 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.   

Fig. 7.11 An Indian elephant