Temperature Belts of World

Temperature Belts of World – UPSC Notes – World Geography

In this article, I aim to guide you through the Temperature Belts of World, specifically focusing on Temperature Distribution on Earth for the UPSC Examination.

The Sun plays a pivotal role as the primary source of atmospheric temperature. Notably, the atmosphere receives a relatively low amount of heat energy directly from the Sun, as the majority of its energy is derived from the long-wave terrestrial radiation.

The processes of conduction, convection, and radiation facilitate the heating and cooling of the atmosphere. This involves the transfer of energy from the Earth, both through direct solar radiation and through these key processes.

Temperature belts of world

The Earth is divided into three primary heat zones, namely:

  • Temperate Zone
  • Torrid Zone
  • Frigid Zone

These zones are determined by their distance from the Equator.

Torrid Zone (Tropical Zone)

The hottest zone on Earth encompasses the region from the Tropic of Cancer (23.5°N), across the Equator (0°), to the Tropic of Capricorn (23.5°S). It is characterized by the direct incidence of the Sun’s rays at least once a year.

Temperate Zone

The habitable heat zone consists of two temperate zones lying between 23½° to 66½° in both hemispheres. These regions experience moderate and tolerable temperatures.

Frigid Zone

The coldest zone is located to the north of the Arctic circle (66.6°N) and to the south of the Antarctic circle (66.5°S), remaining permanently frozen. Sunlight is scarce for most months of the year in this zone.

Importance of the Heat Zones

The division of the Earth into distinct heat zones serves a crucial role in comprehending climate changes and studying weather conditions globally.

Factors affecting Temperature patterns on the globe

The following factors control the distribution of temperature on the earth’s surface-

  • Latitude
  • Altitude
  • Effect of ocean and Seas
  • Effect of local winds
  • Effect of continentality
  • Effect of slope aspect


  • Higher temperatures near the Equator
  • Lower temperatures away (North & South Pole) from the Equator
  • Surface curvature of the Earth results in varying angles of the Sun’s vertical rays

Transparency of Atmosphere

  • Aerosols (smoke, soot), dust, water vapor, clouds impact transparency
  • Scattering occurs if radiation wavelength (X) is more than obstructing particle radius
  • Total reflection happens if wavelength is less than obstructing particle size
  • Solar radiation absorption occurs with obstructing particles like water vapor, ozone, carbon dioxide, or clouds
  • Most received light is scattered light

Land-Sea Differential

  • Higher albedo of land than oceans, especially snow-covered areas (reflecting 70%-90% of insolation)
  • Sunlight penetration is greater in water (up to 20 meters) compared to land (up to 1 meter), affecting cooling and heating rates

Earth’s Distance from Sun

  • Earth’s revolution causes varying distances from the sun
  • Aphelion (farthest) occurs on July 4th (152 million km)
  • Perihelion (nearest) occurs on January 3rd (147 million km)
  • Annual insolation slightly more on January 3rd, but effects are mitigated by factors like land-sea distribution and atmospheric circulation, minimizing impact on daily weather changes


Sunspots are formed on the outer surface due to periodic disturbances and explosions. The quantity of sunspots fluctuates annually, completing a cycle in 11 years. During this cycle, the energy emitted from the sun intensifies. As the number of sunspots rises, the amount of insolation received by the Earth’s surface also increases.


Altitude refers to the height above sea level.

  • High altitude (such as on mountains) correlates with low temperature.
  • Low altitude (on the land surface) corresponds to high temperature.


  • At higher altitudes, the atmospheric volume decreases, leading to reduced water vapor content in the air.
  • With the atmosphere absorbing less heat, temperatures at higher altitudes drop.

Distance from the Sea

  • The variance in land and water heating impacts the temperature of coastal areas differently compared to inland locations.
  • Maritime Influence
    • In summer, when the sea is cooler than the land, it reduces the temperature of coastal areas.
    • In winter, when the sea is warmer than the land, it moderates winter temperatures, keeping coastal places warmer.
  • Continental Influence
    • Inland locations, situated within large continents or landmasses, experience continental influence, unaffected by the sea due to considerable distances.
    • Rapid land heating results in hotter summers compared to coastal areas at similar latitudes.

Ocean Currents

  • Ocean currents are substantial water flows in the oceans, formed by winds over the water surface.
  • Two types: cold currents transporting water from polar regions and warm currents carrying warm water to polar regions.
  • Ocean currents can impact nearby coastal temperatures, with warm currents maintaining warmth in winter and cold currents lowering temperatures if moving along the coast.

Types of Land Surface

  • Dense Forest
    • The presence of dense vegetation obstructs direct solar radiation, keeping the ground cool.
  • In the City
    • Concrete surfaces in urban areas tend to maintain high air temperatures.
    • Concrete absorbs heat during the day and retains it at night.


  • Aspect refers to the direction a slope faces in relation to the sun.
  • In tropical areas, aspect is less crucial due to the high sun position during mid-day.
  • In temperate areas, where the sun is at a lower angle in winter, aspect influences temperatures.
  • In the northern hemisphere, south-facing slopes receive greater solar radiation concentration and are usually warmer than north-facing slopes.

Mean Annual Temperature Distribution

  • Isotherm – An imaginary line connecting places with equal temperatures.
  • The horizontal or latitudinal distribution of temperature is depicted using a map with isotherms.
  • When drawing an isotherm, the effects of altitude are disregarded, and all temperatures are standardized to sea levels.

General Characteristics of Isotherms

  • Generally follow the parallels: Isotherms closely align with latitude parallels, as the same insolation is received by all points on the same latitude.
  • Sudden bends at ocean-continent boundaries: Due to differential heating of land and water, temperatures above oceans and landmasses can vary even on the same latitude (related to land-sea differential affecting temperature distribution).
  • Narrow spacing between isotherms indicates a rapid temperature change (high thermal gradient).
  • Wide spacing between isotherms indicates a gradual or slow temperature change (low thermal gradient).

General Temperature Distribution

  • Highest temperatures prevail in tropics and sub-tropics due to high insolation.
  • Lowest temperatures are observed in polar and subpolar regions and continental interiors due to continentality.
  • In continental interiors, the absence of ocean moderating effects results in the highest diurnal and annual temperature ranges.
  • Least diurnal and annual temperature ranges occur in oceans due to the high specific heat of water and water mixing.
  • Low temperature gradients are found over tropics (constant overhead sun) and high temperature gradients over middle and higher latitudes (varying sun’s path).
  • Temperature gradients are typically low over the eastern margins of continents (warm ocean currents influence).
  • Temperature gradients are usually high over the western margins of continents (cold ocean currents influence).
  • Irregular isotherms over the northern hemisphere due to enhanced land-sea contrast, making the northern hemisphere warmer.
  • The thermal equator (ITCZ) generally lies to the north of the geographical equator.
  • Isotherms exhibit a poleward shift in areas with warm ocean currents (e.g., North Atlantic Drift, Gulf Stream, Kurishino Current, North Pacific Current).
  • Mountains, like the Rockies and Andes, obstruct oceanic influence, impacting the horizontal temperature distribution in North and South America.

Inter-Tropical Convergence Zone (ITCZ)

The Inter-Tropical Convergence Zone (ITCZ) is a wide trough of low pressure located in equatorial latitudes. It is formed by the convergence of the northeast and southeast trade winds. While generally parallel to the equator, the ITCZ shifts north or south in tandem with the apparent movement of the sun.

Seasonal Temperature Distribution

  • Understanding global temperature distribution involves studying temperatures in January and July.
  • Temperature distribution is typically represented on maps using isotherms—lines connecting places with equal temperatures.
  • The influence of latitude on temperature is evident, with isotherms generally parallel to latitude lines.
  • Deviations from this pattern are more pronounced in January, especially in the northern hemisphere.
  • The larger land surface area in the northern hemisphere enhances the effects of landmasses and ocean currents on temperature distribution.

Seasonal Temperature Distribution – January

  • In January, winter prevails in the northern hemisphere and summer in the southern hemisphere.
  • Westerlies bring higher temperatures to the western margins of continents, making them warmer than their eastern counterparts.
  • A close temperature gradient is observed near the eastern margins of continents.
  • Isotherms demonstrate a more regular behavior in the southern hemisphere during January.

Northern Hemisphere

  • Isotherms exhibit northward deviation over the ocean and southward deviation over the continent, notably seen in the North Atlantic Ocean.
  • Presence of warm ocean currents like the Gulf Stream and North Atlantic Drift causes a poleward shift in the isotherms, indicating the oceans’ ability to transport high temperatures northward.
  • Equatorward bend of isotherms over northern continents signals landmass overcooling, allowing polar cold winds to penetrate southwards, particularly pronounced in the Siberian plain.
  • Lowest temperatures are recorded over northern Siberia and Greenland.

Southern Hemisphere

  • Oceanic influence is prominent in the southern hemisphere, with isotherms generally parallel to latitudes and temperature variations more gradual compared to the northern hemisphere.
  • A high-temperature belt is present around 30°S latitude in the southern hemisphere.
  • The thermal equator is located south of the geographical equator, influenced by the Intertropical Convergence Zone (ITCZ) shifting southwards with the apparent movement of the sun.

Seasonal Temperature Distribution – July

  • In July, summer occurs in the northern hemisphere, while the southern hemisphere experiences winter. The isothermal pattern is opposite to that of January.
  • During July, isotherms typically run parallel to latitudes.
  • Equatorial oceans exhibit warmer temperatures, exceeding 27°C.
  • Over land, temperatures surpass 30°C in the subtropical continental region of Asia, along the 30° N latitude.

Northern Hemisphere

  • The highest temperature range exceeds 60°C in the northeastern part of the Eurasian continent due to continentality.
  • The least temperature range, only 3°C, is observed between 20° S and 15° N.
  • Over northern continents, a poleward bend of isotherms signifies overheating of landmasses, allowing hot tropical winds to penetrate far into the northern interiors.
  • Isotherms over northern oceans exhibit an equatorward shift, indicating cooler oceans capable of carrying moderating effects into tropical interiors. Lowest temperatures occur over Greenland.
  • The highest temperature belt spans northern Africa, West Asia, northwest India, and the southeastern USA. Temperature gradient follows an irregular zig-zag path in the northern hemisphere.

Southern Hemisphere

  • In the southern hemisphere, the gradient becomes regular but displays a slight bend toward the equator at the edges of continents.
  • The thermal equator is now positioned north of the geographical equator.

Vertical Distribution of Temperature

  • The normal lapse rate is uniform at a given level within the troposphere across all altitudes.
  • At the Tropopause, the lapse rate reaches zero, indicating no change in temperature.
  • In the lower stratosphere, the lapse rate remains constant for some height, with higher temperatures over the poles due to proximity to the Earth.

Temperature Anomaly

  • Temperature anomaly or thermal anomaly is the difference between the mean temperature of a place and the mean temperature of its parallel (latitude).
  • The largest anomalies occur in the northern hemisphere, and the smallest occur in the southern hemisphere.

The thermal equator represents a global isotherm with the highest mean annual temperature at each longitude worldwide. It does not align with the geographical equator.

While the highest absolute temperatures occur in the Tropics, the highest mean annual temperatures are recorded at the equator. However, due to regional geography, including factors like mountain ranges and ocean currents, creating variations in temperature gradients, the location of the thermal equator differs from that of the geographic Equator.

Considering the Earth’s orbit, where it reaches perihelion (minimum distance from the Sun) in early January and aphelion (maximum distance) in early July, the angle of incidence of the sun’s rays is low in the tropics during the respective winter seasons in each hemisphere. Consequently, the average annual temperature in tropical regions is lower than that observed near the equator, as the change in the angle of incidence is minimal at the equator.

The thermal equator shifts north and south with the corresponding north-south movement of the Sun’s vertical rays. However, the annual average position of the thermal equator is at 5° N latitude. This is because the highest mean annual temperature shifts more significantly northward during the summer solstice compared to its southward shift during the winter solstice.


In conclusion, the concept of the Temperature Belts of the World provides a systematic framework for understanding the distribution of temperatures across the globe. Divided into key zones like the Torrid, Temperate, and Frigid, these belts are determined by factors such as latitude, proximity to the equator, and land-sea differentials. The influence of sun, atmosphere, and ocean currents further contributes to the intricate patterns of temperature variation. Recognizing the significance of these temperature belts is crucial for comprehending climate dynamics, weather patterns, and the impact on ecosystems. Whether studying the equatorial heat, temperate climates, or polar cold, the Temperature Belts model serves as a valuable tool for exploring the Earth’s diverse and dynamic thermal environments.

FAQs on Temperature Belts of World

What are the Temperature Belts of the World?

Answer: The Temperature Belts of the World refer to distinct geographical zones characterized by specific temperature patterns, including the Torrid Zone, Temperate Zone, and Frigid Zone.

How are these Temperature Belts defined?

Answer: The Temperature Belts are primarily determined by factors such as latitude, proximity to the equator, and land-sea differentials, dividing the Earth into regions with similar temperature characteristics.

What are the key zones in the Temperature Belts model?

Answer: The key zones include the Torrid Zone (Tropical Zone), Temperate Zone, and Frigid Zone, each exhibiting unique temperature characteristics based on their geographical location.

How does latitude influence Temperature Belts?

Answer: Latitude plays a crucial role, with the Torrid Zone situated near the equator experiencing higher temperatures, while the Frigid Zone, located near the poles, encounters colder conditions.

What factors contribute to temperature variations within the Temperature Belts?

Answer: Sun exposure, atmospheric conditions, and ocean currents significantly contribute to temperature variations within the Temperature Belts, creating diverse thermal environments across the globe.

Why is the concept of Temperature Belts important?

Answer: Understanding Temperature Belts is essential for comprehending climate dynamics, weather patterns, and their impact on ecosystems, providing valuable insights into the Earth’s diverse thermal environments.

How do ocean currents influence Temperature Belts?

Answer: Ocean currents play a role in redistributing heat, impacting the temperature of coastal areas. Warm currents can moderate temperatures, while cold currents may result in lower temperatures.

What role do land-sea differentials play in Temperature Belts?

Answer: Land-sea differentials contribute to temperature variations, with land heating up or cooling down more rapidly than oceans. This influence is especially pronounced in continental interiors.

Are Temperature Belts static throughout the year?

Answer: No, Temperature Belts experience seasonal variations. For example, the Torrid Zone may have different characteristics during summer and winter, influencing global weather patterns.

How does the concept of Temperature Belts contribute to climate studies?

Answer: The Temperature Belts model provides a fundamental framework for climate studies, aiding in the analysis of temperature distribution, weather phenomena, and broader climate dynamics on a global scale.

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