UPSC MainsGEOGRAPHY-PAPER-I201610 Marks150 Words
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Q2.

Differentiate between insolation and temperature and explain anomalous temperature.

How to Approach

This question requires a clear understanding of fundamental climatological concepts. The approach should begin by defining insolation and temperature, highlighting their differences. Then, a detailed explanation of anomalous temperature, including its causes and significance, is crucial. Structure the answer by first defining the terms, then contrasting them, and finally elaborating on anomalous temperature with examples. Focus on the factors influencing each and their interrelationship.

Model Answer

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Introduction

Insolation, representing the radiant energy received from the sun, and temperature, a measure of the warmth of the atmosphere, are fundamental elements of the Earth’s climate system. While often used interchangeably in common parlance, they are distinct concepts. Anomalous temperature refers to a significant deviation from the average temperature for a given location and time period. Understanding these concepts is vital for comprehending global climate patterns and predicting weather phenomena. This answer will differentiate between insolation and temperature and explain the phenomenon of anomalous temperature.

Insolation vs. Temperature

Insolation (Incoming Solar Radiation) is the total amount of solar radiation reaching a given surface. It is expressed in calories per square centimeter per minute. Factors influencing insolation include:

  • Solar Constant: The amount of solar energy received per unit area perpendicular to the sun’s rays.
  • Earth’s Orbital Variations: Eccentricity, obliquity, and precession affect the amount and distribution of insolation.
  • Atmospheric Absorption: Gases like ozone, water vapor, and carbon dioxide absorb solar radiation.
  • Latitude: Angle of incidence of solar radiation varies with latitude.
  • Season: Earth’s tilt causes seasonal variations in insolation.

Temperature, on the other hand, is a measure of the average kinetic energy of the molecules in a substance. It is typically measured in Celsius (°C) or Fahrenheit (°F). Temperature is influenced by:

  • Insolation: The primary driver of temperature.
  • Latitude: Temperature generally decreases with increasing latitude.
  • Altitude: Temperature decreases with increasing altitude (lapse rate).
  • Proximity to Water Bodies: Water has a high specific heat capacity, moderating temperatures.
  • Ocean Currents: Warm and cold currents influence coastal temperatures.
  • Atmospheric Circulation: Wind patterns distribute heat around the globe.

The key difference lies in that insolation is the *input* of energy, while temperature is the *response* to that energy. Insolation is a measure of radiation, while temperature is a measure of heat.

Anomalous Temperature

Anomalous temperature refers to a departure from the long-term average temperature for a specific location and time. It is calculated by subtracting the average temperature from the observed temperature. A positive anomaly indicates a warmer-than-average temperature, while a negative anomaly indicates a cooler-than-average temperature.

Causes of Anomalous Temperature

  • Climate Change: Increased greenhouse gas concentrations are leading to a global warming trend, resulting in positive temperature anomalies.
  • El Niño-Southern Oscillation (ENSO): El Niño events cause warmer-than-average temperatures in the central and eastern tropical Pacific Ocean, leading to global temperature anomalies. La Niña causes cooler anomalies.
  • Volcanic Eruptions: Volcanic aerosols can reflect solar radiation, causing temporary cooling and negative temperature anomalies.
  • Changes in Ocean Currents: Shifts in ocean currents can redistribute heat, leading to regional temperature anomalies.
  • Land Use Changes: Deforestation and urbanization can alter local temperature regimes.

Significance of Anomalous Temperature

  • Climate Monitoring: Anomalies are a more useful indicator of climate change than absolute temperatures, as they filter out seasonal variations.
  • Weather Forecasting: Anomalies can help predict future weather patterns.
  • Impact Assessment: Anomalies can be used to assess the impacts of climate change on ecosystems and human societies.

Example: The record-breaking heatwaves experienced in Europe in 2022 and 2023 were characterized by significant positive temperature anomalies, exceeding 2°C above the average for that time of year. This led to widespread droughts, wildfires, and heat-related illnesses.

Feature Insolation Temperature
Definition Incoming solar radiation Measure of heat/kinetic energy
Units cal/cm²/min °C or °F
Influencing Factors Earth’s orbit, atmospheric absorption, latitude Insolation, altitude, proximity to water

Conclusion

In conclusion, while insolation represents the energy input into the Earth’s system, temperature reflects the resulting heat. Anomalous temperatures, deviations from long-term averages, are crucial indicators of climate change and variability. Understanding these concepts is essential for monitoring climate patterns, predicting weather events, and assessing the impacts of a changing climate. Continued monitoring of temperature anomalies is vital for informed decision-making and mitigation strategies.

Answer Length

This is a comprehensive model answer for learning purposes and may exceed the word limit. In the exam, always adhere to the prescribed word count.

Additional Resources

Key Definitions

Albedo
The fraction of solar radiation reflected by a surface. Higher albedo means more reflection and less absorption of solar energy.
Lapse Rate
The rate at which temperature decreases with increasing altitude in the atmosphere. The average lapse rate is approximately 6.5°C per kilometer.

Key Statistics

Global average temperature has increased by approximately 1.1°C since the pre-industrial era (1850-1900).

Source: IPCC Sixth Assessment Report (2021)

The Arctic is warming at a rate nearly twice as fast as the global average.

Source: Arctic Report Card (National Oceanic and Atmospheric Administration - NOAA, latest available data)

Examples

Urban Heat Island Effect

Cities tend to be warmer than surrounding rural areas due to the absorption of solar radiation by buildings and pavement, and reduced evapotranspiration. This creates a localized temperature anomaly.

Frequently Asked Questions

What is the difference between weather and climate?

Weather refers to the short-term atmospheric conditions at a specific time and place, while climate refers to the long-term average of weather patterns in a region.

Topics Covered

ClimatologyPhysical GeographyTemperatureInsolationClimate Change