World Climate and Climate Change

Correct Option: (c) Mean monthly temperature of all the months more than 18°C

Justification: Koeppen's 'A' type (Tropical Humid Climate) is defined by the criterion that the mean monthly temperature of every month of the year is more than 18°C. This distinguishes it from other climate types. High rainfall in all months is a feature of only the 'Af' sub-type, not the entire 'A' group.

Correct Option: (d) Empirical

Justification: Koeppen's classification is called empirical because it is based on observed and recorded data of temperature and precipitation (i.e., actual observed climatic data), rather than on the causes or origin of climate. A genetic classification, by contrast, is based on the causes that produce the climate.

Correct Option: (d) "Am"

Justification: Most of the Indian Peninsula experiences a tropical monsoon climate. In Koeppen's classification, 'Am' stands for Tropical Monsoon Climate, characterised by high annual rainfall concentrated in a few months (monsoon season) with a short dry season. This fits the climatic conditions of the Indian Peninsula perfectly.

Correct Option: (b) 1998

Justification: According to climatic records, the year 1998 was recorded as the warmest year globally. This was partly attributed to a strong El Niño event combined with the long-term trend of global warming caused by increasing greenhouse gas concentrations in the atmosphere.

Correct Option: (b) A—C—D—E

Justification: In Koeppen's classification:
- A = Tropical Humid climates (humid)
- C = Warm Temperate (humid)
- D = Cold Snow Forest (humid)
- E = Polar climates (humid/cold)

Type B represents dry (arid and semi-arid) climates. Therefore, the group A–C–D–E correctly represents humid conditions, while B is excluded.

Given: Koeppen's empirical system of climate classification.

Answer:

Koeppen used two main climatic variables for his classification:
1. Temperature – mean monthly and annual temperature values.
2. Precipitation (Rainfall) – mean monthly and annual precipitation values.

Based on these two variables, he identified specific threshold values and seasonal patterns to define different climate types and sub-types, denoted by capital and small letters (e.g., A, B, C, D, E and f, m, s, w, etc.).

Answer:

| Basis | Empirical Classification | Genetic Classification |
|---|---|---|
| Basis | Based on observed/recorded climatic data (temperature and precipitation) | Based on the causes or origin of climate (e.g., air masses, pressure belts) |
| Example | Koeppen's classification | Flohn's classification |
| Nature | Descriptive and statistical | Explanatory and process-based |

In short, the empirical system classifies climate by *what is observed*, while the genetic system classifies climate by *why it occurs* — i.e., the atmospheric processes and controls responsible for producing that climate.

Answer:

The following types of climates have a very low (small) range of temperature:

1. Equatorial Climate ('Af') – Located near the equator, it receives uniform solar radiation throughout the year, resulting in uniformly high temperatures with very little seasonal variation. The diurnal and annual range of temperature is very low.

2. Marine/Oceanic Climate ('Cfb') – Coastal areas influenced by the sea experience the moderating effect of the ocean, which keeps temperatures equable (cool summers and mild winters), resulting in a very low annual range of temperature.

In general, low-latitude coastal and equatorial regions have the lowest temperature ranges.

Answer:

Sunspots are dark patches on the surface of the Sun associated with intense magnetic activity and increased solar energy output.

If sunspots increase, the following climatic conditions are likely to prevail:
- Increased solar radiation reaches the Earth, leading to a rise in temperature globally.
- This may cause increased evaporation, leading to more rainfall and storminess in certain regions.
- Studies suggest a correlation between high sunspot activity and warmer and wetter conditions on Earth.
- Conversely, periods of very few sunspots (like the Maunder Minimum) have been associated with cooler climates (e.g., the Little Ice Age).

Thus, an increase in sunspots is generally associated with warmer global temperatures and increased precipitation.

Given: Koeppen's climate types 'A' (Tropical Humid) and 'B' (Dry Climates).

Comparison between 'A' type and 'B' type climates:

| Feature | 'A' Type (Tropical Humid) | 'B' Type (Dry/Arid) |
|---|---|---|
| Temperature | Mean monthly temperature of all months > 18°C; uniformly high | High during day, low at night; large diurnal range |
| Precipitation | Adequate to heavy rainfall; evaporation < precipitation | Evaporation exceeds precipitation; very low rainfall |
| Humidity | High humidity throughout the year | Very low humidity |
| Seasons | No cold season; wet and dry seasons in sub-types | No distinct wet season; dry conditions dominate |
| Location | Equatorial and tropical regions (0°–25° lat.) | Tropical and mid-latitude deserts and steppes (15°–60° lat.) |
| Sub-types | Af (Rainforest), Am (Monsoon), Aw (Savanna) | BWh, BWk (Desert), BSh, BSk (Steppe) |
| Vegetation | Dense tropical rainforests, savanna grasslands | Sparse xerophytic plants, cacti, thorny shrubs |
| Example regions | Amazon Basin, Congo Basin, Indian Peninsula | Sahara Desert, Arabian Desert, Thar Desert |

Conclusion: The fundamental difference is that 'A' type climates are characterised by adequate moisture and high temperatures, supporting lush vegetation, while 'B' type climates are defined by moisture deficiency (evaporation > precipitation), supporting only sparse, drought-resistant vegetation.

Given: Koeppen's 'C' type (Warm Temperate/Mesothermal) and 'A' type (Tropical Humid) climates.

Vegetation in 'A' Type Climate (Tropical Humid):

1. Af (Tropical Rainforest): Dense, multi-layered tropical evergreen rainforests with a huge variety of species — tall trees forming a continuous canopy, epiphytes, lianas, and rich biodiversity. Example: Amazon rainforest, Congo Basin.

2. Am (Tropical Monsoon): Tropical deciduous and semi-evergreen forests; trees shed leaves during the dry season. Example: Indian monsoon forests.

3. Aw (Tropical Savanna): Tropical grasslands (savanna) with scattered trees like acacia and baobab. Example: African savanna.

Vegetation in 'C' Type Climate (Warm Temperate/Mesothermal):

1. Cfa/Cwa (Humid Subtropical): Broadleaf evergreen and mixed forests; also supports grasslands (prairies/pampas) in continental interiors.

2. Cfb (Marine West Coast): Temperate deciduous forests — oak, beech, maple, elm; dense and lush due to adequate year-round rainfall.

3. Cs (Mediterranean): Scrub forests and shrublands (Chaparral/Maquis); drought-resistant, hard-leaved (sclerophyllous) plants like olive, cork oak, lavender. Vegetation is adapted to dry summers and wet winters.

Conclusion: 'A' type climates support the world's most diverse and dense forests, while 'C' type climates support a range from temperate deciduous forests to Mediterranean scrublands, depending on the sub-type.

Greenhouse Gases — Meaning:

The Earth's atmosphere contains certain gases that allow incoming short-wave solar radiation to pass through but absorb and re-emit the outgoing long-wave (infrared) radiation from the Earth's surface. This process traps heat in the lower atmosphere, keeping the Earth warm — similar to the glass panels of a greenhouse. The gases responsible for this effect are called Greenhouse Gases (GHGs).

- Without the natural greenhouse effect, the average temperature of the Earth would be about –18°C instead of the current +15°C.
- However, human activities (burning fossil fuels, deforestation, industrialisation, agriculture) have increased the concentration of these gases, enhancing the greenhouse effect and causing global warming and climate change.

List of Major Greenhouse Gases:

| S.No. | Greenhouse Gas | Chemical Formula | Major Source |
|---|---|---|---|
| 1. | Carbon Dioxide | $CO_2$ | Burning of fossil fuels, deforestation |
| 2. | Methane | $CH_4$ | Wetlands, livestock, paddy fields, landfills |
| 3. | Nitrous Oxide | $N_2O$ | Agricultural soils, fertilisers, combustion |
| 4. | Water Vapour | $H_2O$ | Evaporation from oceans and water bodies |
| 5. | Ozone | $O_3$ | Photochemical reactions in atmosphere |
| 6. | Chlorofluorocarbons (CFCs) | CFCs | Refrigerants, aerosols (man-made) |
| 7. | Hydrofluorocarbons (HFCs) | HFCs | Industrial processes |
| 8. | Sulphur Hexafluoride | $SF_6$ | Electrical industry |

Conclusion: Greenhouse gases are essential for life on Earth in their natural concentrations, but their rapid increase due to human activities is the primary driver of contemporary global warming and associated climate change.