12 World Climate and climate change
NCERT Questions:
- Multiple choice questions:
(i) Which one of the following is suitable for Koeppen’s, “A” type of climate?
a) High rainfall in all the months
b) Mean monthly temperature of the coldest month more than freezing point
c) Mean monthly temperature of all the months more than 18˚ C.
d) Average temperature for all the months below 10˚ C
Ans. a) High rainfall in all the months
(ii) Koeppen’s system of classification of climates can be termed as:
a) Applied
b) Systematic
c) Genetic
d) Empirical
Ans. d) Empirical
(iii) Most of the Indian peninsula will be grouped according to Koeppen’s system under:
a) Af
b) BSh
c) Cfb
d) Am
Ans. d) Am
(iv) Which one of the following years is supposed to have recorded the warmest temperature the world over?
a) 1990
b) 1998
c) 1985
d) 1950
Ans. b) 1998
(v) Which one of the following groups of 4 climates represents humid conditions?
a) A-B-C-E
b) A-C-D-E
c) B-C-D-E
d) A-C-D-F
Ans. b) A-C-D-E
- Answer the following questions in about 30 words:
(i) Which two climate variables are used by Koeppen for classification of the climate?
Ans. It is an empirical classification based on variables of mean annual and mean monthly temperature and precipitation data. He introduced the use of capital and small letters to designate climate groups and types. Although developed in 1918 and modified over a period of time Koeppen’s scheme is still popular and in use. Koeppen recognised 5 major climatic groups four of them are based on temperature and one on precipitation. Koeppen 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 for classifying the climates.
(ii) How is the genetic system of classification different from the empirical one?
Ans. Empirical classification is based on observed data, particularly on temperature and precipitation, while genetic classification attempts to organise climates according to their causes.
(iii) Which type of climate has very low range of temperature?
Ans. Tropical wet climate has very low range of temperature. It is found near the equator. The major areas are the Amazon basin in South America, Western Equatorial Africa and the islands of East Indies. Significant amount of rainfall occurs in every month of the year and thunder showers in the afternoon. The temperature is uniformly high and the annual range of temperature is negligible. The maximum temperature on any day is around 30˚ C while the minimum temperature is around 20˚ C.
Tropical Evergreen forest with dense canopy cover and large biodiversity are found in this climate.
(iv) What type of climatic conditions would prevail if the sun spots increases?
Ans. Sunspots are dark and cooler patches on the sun, which increases and decreases in a cyclical manner. According to some meteorologist when the number of sunspots increases, cooler and wetter weather and greater storminess occur. A decrease in a sunspots numbers is associated with warm and dryer conditions.
Answer the following questions in about 150 words:
Make a comparison of the climatic conditions between the ‘A’ And ‘B’ type of climate.
Ans.
| Af | Tropical wet | No dry season. The driest month has at least 60 mm (2.4’) of rain. Rainfall is generally evenly distributed throughout the year. All average monthly temperatures are greater than 18˚ C (64˚ F). |
| Am | Tropical monsoon | Pronounced wet season. Short dry season. There are one or more months with less than 60 mm (2.4) rainfall. All average monthly temperatures are greater than 18˚ C (64˚ F). Highest annual temperature occurs just prior to the rainy season. |
| Aw | Tropical Wet and Dry Climate | Winter dry season. There are more than 2 months with less than 60 mm (2.4’) of rainfall. All average monthly temperatures are greater than 18˚ C. 64˚ F. |
| BSh | Subtropical Dry Semiarid (Steppe) | Low latitude dry. Evaporation exceeds precipitation on average but is less than potential evaporation. Average temperature is more than 18˚ C (64˚ F). |
| BSk | Mid latitude dry, semiarid (Steppe) | Mid latitude dry. Tabulation exceeds precipitation on average, but is less than potential evaporation. Average temperature is less than 18 degree C, 64 degree F. |
| BWh | Subtropical Dry Arid (desert) | Low latitude desert. Evaporation exceeds precipitation on average, but is less than half potential evaporation. Average temperature is more than 18 degree C, 64 degree F. Frost is absent. Or infrequent. |
| BWk | Mid latitude dry aired desert | Mid latitude desert evaporation exceeds precipitation on average. But is less than half potential evaporation. Average temperature is less than 18 degree C. 64 degrees F winter has. Below freezing temperatures. |
(ii) What type of vegetation would you find in the ‘C’ and ‘A’ type(s) of climate?
Ans. ‘A’ Tropical Humid Climates: Tropical humid climates exist between Tropic of Cancer and Tropic of Capricorn. The sun being overhead, climate is hot and humid, annual range of temperature is very low and annual rainfall is high. The tropical group is divided into 3 types:
a) Af – Tropical wet climate
b) Am – Tropical monsoon climate
c) Aw – Tropical wet and dry climate
‘C’ Warm temperate (humid throughout the year and the presence of Inter-tropical convergence zone, ITCZ) make the latitudes climate extend from 30˚ to 50˚ of latitude, mainly on the eastern and western margins of continents. These climates generally have warm summers with mild winters. They are grouped into 4 types:
a) CWa – Humid subtropical that is dry in winter and hot in summer
b) Cs – Mediterranean
c) Cfa – Humid subtropical, that is no dry season and mild winter
d) Cfb – Marine West Coast Climate
(iii) What do you understand by the term greenhouse gases? Make a list of greenhouse gases.
Ans. The term greenhouse is derived from the analogy to a greenhouse used in cold areas for preserving heat. Greenhouse is made up of glass. The glass, which is transparent to incoming shortwave solar radiation, is opaque to outgoing long wave radiation. The glass therefore allows in more radiation and prevents the long wave radiation going outside the glass house, causing the temperature inside the glass house structure warmer than outside. Greenhouse gases are those gases which cause global warming and result in rise in atmospheric temperature. These gases absorb long wave radiation, the process that warm the atmosphere are often collectively referred to as the greenhouse effect.
Greenhouse gases (GHGs). The primary GHGs of concern today are carbon dioxide. Chlorofluorocarbons (CFCs) Methane (CH4) Nitrous oxide (N2O) ozone (O3) some other gases, such as nitric oxide (NO) and carbon monoxide (CO), easily react with. GHGs and affect their concentration in the atmosphere. The effectiveness of any given GHG molecule will depend on the magnitude of the increase in its concentration, its lifetime in the atmosphere, and the wavelength of radiation that it absorbs.
Question Bank:
- Which one of the following is suitable for Koeppen’s ‘A’ type of climate.
a) High rainfall in all the months
b) Mean monthly temperature of the coldest month more than freezing point
c) Monthly temperature of all the months more than 18˚C
d) Average temperature for all the months below 10˚C
Ans. a) High rainfall in all the months
- Koeppen’s system of classification of climate can be termed as:
a) Applied
b) Systematic
c) Genetic
d) Empirical
Ans. d) Empirical
- Most of the Indian peninsula will be grouped according to Koeppen’s system under
a) ‘Af’
b) ‘BSH’
c) ‘Cfb’
d) ‘Am’
Ans. d) ‘Am’
- Which one of the following years is supposed to have recorded the warmest temperature the world over?
a) 1990
b) 1998
c) 1885
d) 1950
Ans. b) 1998
Short answer type questions:
- Which two climate variables are used by Koeppen for classification of the climate?
Ans. The Koeppen climatic classification is based on mean annual and mean monthly temperature and precipitation data.
- How is the genetic system of classification different from the empirical one?
Ans. Genetic classification attempts to organize climates according to their causes. Applied classification is for specific purpose. Empirical classification is easy to understand and data requirement are minimal. Here the classification is largely based on annual and monthly means of temperature and precipitation.
- Which type of climatic conditions would prevail if the sun spots increase?
Ans. When the number of sun spots increases cooler and better weather and greater storminess occur.
- Make a comparison of the climatic conditions between the ‘A’ and ‘B’ types of climate.
Ans.
| Group ‘A’ type of climate | Group ‘B’ type of climate |
| a) These are also known as tropical humid climates. b) Annual range of temperature is very low and annual rainfall is high. c) This type of climate exists between Tropic of Cancer and Tropic of Capricorn.
d) This region is usually wet due to the monsoon but it has a short dry season as well. e) This group is divided into 3 types Tropical wet Tropical monsoon Tropical wet and dry
| a) These are known as dry climates.
b) Annual rainfall is very low
c) This type of climate exists between 15˚ to 60˚ North and South of the equator dividing the region into low and mid-latitudes. d) Dry and arid conditions are common in this particular climate. e) This group is divided into steppe and desert climate which are: Subtropical steppe Subtropical desert Mid latitude steppe Mid latitude desert |
- What type of vegetation would you find in the ‘A’ and ‘C’ types of climate?
Ans. Since type ‘A’ is associated with tropical humid climates the vegetation consists of tropical rainforest which consist of evergreen trees bushes and shrubs deciduous forest and tree shredded grasslands.
And type ‘C’ is associated with warm temperate mid latitude climates the vegetation here consists of evergreen trees like pine and cypress trees which are mixed with deciduous trees such as oaks. Then fruit trees and vines such as grapes figs olives and citrus fruits grow well here.
- What do you understand by the term greenhouse gases? Make a list of greenhouse gases.
Ans. The term greenhouse is derived from a method that the people use in cold areas for preserving heat basically a greenhouse is a room cottage or a compartment made up of glass. Since glass is transparent, solar radiation gets in but it gets trapped inside and does not go outside. This is the Sun’s short wave radiation trapped within the glass house. It eventually increases the temperature inside the glass house which keeps everything inside warmer than outside. A very good example to understand this concept is to imagine the car parked outside on a hot summer day. When one enter the car since the windows are closed. One feels more heat inside than outside; this is same that happens in a greenhouse, where the incoming solar radiation is trapped inside a glass house for the preservation of heat.
The primary greenhouse gases are:
Carbon dioxide CO2
Chlorofluorocarbons CFC
Methane CH4
Nitrous oxide N2O
Ozone O3
Nitric oxide NO
Carbon Monoxide Co