Chapter - 12
Climate and Climate Change of the World
️ Climate :-
Our life and our economic activities (eg agriculture, trade, industry etc.) are all influenced and sometimes controlled by climate.
️ Classification of Climate :-
The first classification of climate was done by the Greeks.
There are three bases of climate classification :-
- आनुà¤à¤µिक ( empirical )
- जननिक Genetic
- Practical Applied or Functional.
Climate is the mean or average of daily weather conditions over a long period of time (at least 30 years).
️ Mediterranean Climate :-
The Mediterranean climate (Cs) is found along the west coast of the continents from 30° to 40° latitudes to the subtropical zone.
️ Climate classification of Koppen :-
Koppen's climate classification (1918) is genetic and empirical. Köppen classified climate on the basis of temperature and precipitation. Thornwait based his climate classification on precipitation effectiveness, thermal efficiency, and potential transpiration.
Koppen identified a close relationship between the distribution of vegetation and climate. He selected certain values of temperature and precipitation and related them to the distribution of vegetation and used these values to classify the climate.
Climate group according to Köppen :-
- Dry
- warm temperate
- cold snow forest
- cold
- Tropical humidity
- high ground
Köppen introduced the use of uppercase and lowercase letters to identify groups and types of climate. Developed in 1918 and modified over time, this method of Koppen is still popular and prevalent today.
Köppen determined five major climate groups, four of which are based on temperature and one on precipitation.
Koppen has denoted humid climate with capital letters A, C, D and E and letter B for dry climate. Climatic groups are divided into several smaller units on the basis of seasonal characteristics of temperature and rainfall and are designated by means of small letters.
️ Tropical climate of Köppen :-
The tropical climate of Köppen is divided into three types, whose names are :-
- Af tropical humid climate
- Am tropical monsoon climate
- Aw Tropical humid climate with dry winters.
️ (Am) Tropical monsoon, short dry season :-
These winds cause heavy rain in summer.
The winter season is usually dry.
This climate is found in the Indian subcontinent, the north-eastern part of South America and northern Australia.
AW Tropical humid and dry climate: -
There is very little rainfall in this type of climate.
The dry season in this climate is long and harsh.
There is often a famine in the dry season.
In areas with this type of climate, deciduous forests and grasslands covered with trees are found.
️ Tropical humid climate :-
Tropical humid climate is found near the equator. The major regions of this climate are the Amazon Basin of South America, Western Equatorial Africa and the islands of South East Asia. In every month of the year there is abundant rainfall with thunderstorms and showers after noon.
The temperature in the equatorial region is uniformly high and the annual temperature difference is negligible. The maximum temperature on any given day is 30 °C and the minimum temperature is 20 °C.
️ Tropical monsoon climate :-
The tropical monsoon climate is found in the Indian subcontinent, the north-eastern part of South America and northern Australia. Heavy rainfall occurs mostly in summer. The winter season is dry.
️ Dry climate :-
Dry climate is characterized by very little rainfall which is not enough for the growth of plants. This climate is found on a large part of the Earth, which flows between 15 ° to 60 ° north and south latitudes from the equator.
️ Desert climate :-
Most of the tropical true deserts are spread between 15° and 60° latitudes in both the hemispheres.
The average temperature in hot deserts is 38 °.
In deserts, the process of evaporation is more than that of precipitation.
Due to high temperature and lack of rainfall, vegetation is rarely found.
️ China equivalent climate :-
This climate is found in the eastern seaboard areas of the continents between the latitudes of 25 ° and 45 ° in both the hemispheres.
The annual average rainfall is 100 cm. There is more rainfall in summer than in winter.
There is both summer and winter season here. Temperatures remain high. The average temperature of the hottest month is 27 centigrade. By the way, the winter season is mild. But sometimes it gets frosty.
In this region, broad-leafed and angle-striped mixed forests are found.
️ Taiga Climate :-
This climate group extends only in the northern hemisphere between 50 and 70 ° north latitudes.
This climate is found in North America from Alaska to Newfoundland and from Scandinavia in Eurasia to Kamchatka Peninsula in the eastern end of Siberia.
In this climate, the summers are short and cold and the winters are long and cold. ,
The action of precipitation is the summer season.
️ Tundra Climate :-
This climate group extends only in the northern hemisphere between 60 to 75 ° north latitudes.
This climate is found in the Arctic coastal belt of North America and Eurasia in the Greenland and snowless coastal areas of Iceland.
The summers are generally mild here, generally the temperature is less than 10 ° C.
It snows here throughout the year.
️ Green house effect :-
The main source of energy on Earth is the Sun. The radiation that reaches the Earth from the Sun is called insolation, that is, the energy received from the Sun is called insolation. This energy received from the Sun is received in the form of short waves. A large part of it is converted into long waves by the surface. Earth's atmosphere deals with rays of different wavelengths of insolation in different ways. Some gases and water vapor present in the atmosphere absorb 90 percent of the long waves converted in the surface. In this way the main source of heating of the atmosphere is long waves ie terrestrial radiation. From this point of view, the atmosphere behaves like a greenhouse or the glass of a motor vehicle. It allows short rays coming from the sun to pass through, But it absorbs the long outgoing rays. This is called green house effect.
️ Major Green House Gases :-
The following are the major green house gases:-
- Carbon dioxide (CO₂)
- Chloro-fluorocarbons (CFCs)
- Methane (CH₄)
- Nitrous oxide (N₂O)
- Ozone ( O₃ )
- Nitric Oxide (NO)
- carbon monoxide CO
Global warming: -
The temperature of the world is increasing due to the greenhouse effect, which is called global warming or warming. Global warming is caused by an increase in the amount of greenhouse gases in the atmosphere.
Effects of global warming: -
The following are the effects of global warming:-
All the ice in the polar regions and mountainous regions will melt.
The sea level will rise, due to which many coastal areas will be submerged. Like Mumbai, Dhaka, Maldives etc.
The salt water of the sea will spoil the fresh water of the earth.
The melting of the glaciers of the mountains will cause floods in the rivers.
Discuss the causes of climate change in the world :-
There are many causes of climate change, which are divided into three categories like astronomical, terrestrial and human :-
Astronomical causes: - Astronomical causes are related to the change in solar energy generated by solar stigmas. Solar spots are dark spots found on the Sun, which decrease and increase in a cyclic sequence as the number of solar spots increases. Conversely, when the number of solar spots decreases, the weather becomes warm. Another astronomical theory is the Milakovich oscillation, which speculates about changes in the Earth's axial tilt around the Sun. All these factors bring about a change in the insolation received from the Sun, which has an effect on the climate.
Earthly causes: - Volcanic eruptions are one of the causes of climate change among the earthly causes. When a volcano erupts, a large amount of aeroceles enter the atmosphere. These aeroceles remain active in the atmosphere for a long time and reduce the solar radiation by blocking the rays coming from the sun. This makes the weather cold.
Human Cause:- Some of these changes are the result of unwanted activities of human beings. These can be reduced by human effort. One such change is global warming, which is caused by the continuous and greater amount of carbon dioxide and other greenhouse gases such as methane and chlorofluorocarbons being transported into the atmosphere by humans.
