When we go out in the morning, we see whether the day is sunny, cloudy, rainy or windy. The daily condition of the atmosphere at a place, with respect to temperature, humidity, rainfall, wind speed and other factors, is called weather. Weather changes very often, sometimes even within a few hours. In this chapter we study weather, the climate of a region, and the remarkable ways in which animals adapt to their climate.
Weather is influenced by the sun, the atmosphere and the Earth's rotation. Meteorologists collect information about temperature, humidity, rainfall and wind speed using instruments, and they use this data to forecast the weather. A weather report tells us the temperature of the day, humidity, rainfall and the wind speed and direction. Humidity is the amount of water vapour present in air, and it is measured by an instrument called a hygrometer, while maximum-minimum thermometers record the highest and lowest temperatures of the day.
Climate is the average weather condition of a place over a long period of time, usually 25 years or more. While weather can change in a few hours, climate changes very slowly. The climate of a place is described by its average temperature, rainfall, humidity and the prevailing winds. For example, we say the climate of Rajasthan is hot and dry, the climate of Kerala is hot and humid, and the climate of the Himalayan region is cold.
Climate is determined by many factors such as the latitude (distance from the equator), altitude (height above sea level), distance from the sea, and the prevailing winds. Places near the equator receive more direct sunlight and are generally hotter, while places at high altitudes are cooler. Coastal areas have a moderate climate because the sea regulates temperature, while inland areas experience extremes of heat and cold. The study of climate helps us understand agriculture, human settlement and the distribution of plants and animals.
The climate of a region strongly affects the plants and animals that live there. Living organisms have special features in their body and behaviour that help them survive in their climate; these features are called adaptations. Adaptations develop over long periods of time and may be structural (relating to body structure), behavioural (relating to habits) or physiological (relating to body functions).
Polar regions are very cold with temperatures below -37°C in winter, and animals there have special adaptations. The polar bear has a thick layer of fat called blubber under its skin and a white, thick fur that keeps it warm and helps it blend with snow for hunting. Its wide feet help it walk on snow, and it can swim well in icy water. In tropical rainforests, which are hot and humid with heavy rainfall, animals like the elephant, monkey, toucan and red-eyed frog show different adaptations. The elephant has a large ear that helps it get rid of extra body heat; monkeys have long grasping tails for moving between trees; the toucan has a long curved beak to reach fruits and defend itself; and the red-eyed frog hides in dark places to keep its body cool and moist. Lions, on the other hand, are found in tropical grasslands where temperatures remain moderate; their light brown colour helps them hide among the dry grass while hunting.
The polar region includes the Arctic and Antarctica, where the climate is extremely cold. Penguins live in Antarctica in large groups called rookeries and keep themselves warm by huddling together. Their bodies are streamlined and covered with waterproof feathers, and they have a layer of fat for insulation. The polar bear, the largest land carnivore in the Arctic, is well adapted to its environment. Its white fur gives camouflage in snow, its thick fat layer (blubber) keeps it warm, its wide feet help in walking on snow, and its sharp claws help it catch prey.
These animals also show behavioural adaptations. Polar bears are good swimmers and can dive to catch seals, their main food. Penguins huddle together for warmth and take turns staying on the outside of the group. Such adaptations show how animals have evolved to survive in the harshest climates on Earth.
Tropical rainforests are found near the equator and have a hot and humid climate with heavy rainfall throughout the year. The animals of these forests are adapted to live on trees (arboreal), since the dense canopy provides food and shelter. Monkeys have long tails that can grasp branches, and strong arms and legs for swinging from tree to tree. The red-eyed frog has sticky pads on its feet to cling to leaves, and it hides in dark, moist places during the day to avoid heat and predators.
The elephant of tropical forests has large ears which help it radiate excess body heat. The toucan has a long curved beak that helps it reach fruits growing on the tips of thin branches, and the bright colour of the beak helps attract a mate. These animals have adapted to the warm, humid conditions of the forest, where camouflage among the green leaves is important for protection. Understanding these adaptations helps us appreciate the diversity of life and the delicate balance between organisms and their environment.
| Region | Climate | Animal Adaptations |
|---|---|---|
| Polar region | Very cold, -37°C | Polar bear: blubber, white fur, wide feet; penguins: huddle, waterproof feathers |
| Tropical rainforest | Hot, humid, heavy rain | Elephant: large ears; monkey: grasping tail; toucan: long beak; red-eyed frog: sticky pads |
| Tropical grassland | Moderate, dry | Lion: light brown colour for camouflage |
| Element of Weather | Instrument |
|---|---|
| Temperature | Maximum-minimum thermometer |
| Humidity (water vapour) | Hygrometer |
| Rainfall | Rain gauge |
| Wind speed | Anemometer |
Weather and climate are closely related but different concepts. Weather is the short-term condition of the atmosphere while climate is the long-term average of weather over many years. The climate of a region determines which plants and animals can live there, and animals have evolved remarkable adaptations to survive. Polar animals like the polar bear and penguin are adapted to extreme cold with fat layers, thick fur and social behaviours, while rainforest animals show adaptations for heat, humidity and life in trees. Studying these adaptations deepens our understanding of the diversity of life and the importance of protecting natural habitats.