{"id":861905,"date":"2025-06-10T15:29:47","date_gmt":"2025-06-10T09:59:47","guid":{"rendered":"https:\/\/leverageedu.com\/discover\/?p=861905"},"modified":"2025-06-10T15:29:47","modified_gmt":"2025-06-10T09:59:47","slug":"ncert-notes-class-11-geography-fundamentals-of-physical-geography-chapter-8-solar-radiation-heat-balance-and-temperature","status":"publish","type":"post","link":"https:\/\/leverageedu.com\/discover\/school-education\/ncert-notes-class-11-geography-fundamentals-of-physical-geography-chapter-8-solar-radiation-heat-balance-and-temperature\/","title":{"rendered":"NCERT Notes Class 11 Geography Fundamentals of Physical Geography Chapter 8: Solar Radiation, Heat Balance and Temperature (Free PDF)"},"content":{"rendered":"\n

Looking for NCERT Class 11 Geography Fundamentals of Physical Geography Chapter 8 Solar Radiation, Heat Balance and Temperature Notes? You\u2019re in the right place! This blog provides simple and clear notes to help you understand the key concepts of this chapter. Whether you’re preparing for exams or need a quick revision, these notes will help you understand the essential ideas without going through the entire textbook. Let\u2019s dive in!<\/p>\n\n\n\n\n\n\n

Explore Notes of Class 11 Fundamentals of Geography<\/strong><\/p>\n\n\n\n

Chapter 1<\/strong><\/a><\/td>Chapter 2<\/strong><\/a><\/td>Chapter 3<\/strong><\/a><\/td>Chapter 4<\/strong><\/a><\/td>Chapter 5<\/strong><\/a><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
Download PDF of NCERT Notes Class 11 Geography Fundamentals of Physical Geography Chapter 8: Solar Radiation, Heat Balance and Temperature<\/strong><\/a><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Introduction<\/h2>\n\n\n\n

The Earth is surrounded by an atmosphere composed of numerous gases that support life. The Earth receives almost all its energy from the Sun in the form of solar radiation, known as insolation. The Earth radiates back an equal amount of energy to space, maintaining a stable temperature over time. Variations in insolation cause pressure differences in the atmosphere, leading to heat transfer through winds. This chapter explains how the atmosphere is heated and cooled and how temperature is distributed across the Earth\u2019s surface.<\/p>\n\n\n\n

Solar Radiation<\/h2>\n\n\n\n

The Earth\u2019s surface receives most of its energy as shortwave solar radiation, termed insolation. The Earth, being a geoid, intercepts only a small portion of the Sun\u2019s energy, receiving an average of 1.94 calories per sq. centimetre per minute at the top of its atmosphere. The solar output varies slightly due to the Earth\u2019s distance from the Sun, being closest (perihelion, 147 million km) on January 3rd and farthest (aphelion, 152 million km) on July 4th. This variation has minimal impact on daily weather due to factors like land-sea distribution and atmospheric circulation.<\/p>\n\n\n\n

Variability of Insolation at the Earth\u2019s Surface<\/h2>\n\n\n\n

The amount and intensity of insolation vary daily, seasonally, and annually due to:<\/p>\n\n\n\n

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  1. Earth\u2019s Rotation:<\/strong> Affects daily insolation patterns.<\/li>\n\n\n\n
  2. Angle of Inclination of Sun\u2019s Rays:<\/strong> At higher latitudes, slanting rays cover more area, reducing energy per unit area and passing through more atmosphere, leading to greater absorption, scattering, and diffusion.<\/li>\n\n\n\n
  3. Length of the Day:<\/strong> Longer days increase insolation.<\/li>\n\n\n\n
  4. Transparency of the Atmosphere:<\/strong> Water vapour, ozone, and other gases absorb near-infrared radiation, while suspended particles scatter visible light, affecting sky colours (e.g., red at sunrise\/sunset, blue sky).<\/li>\n\n\n\n
  5. Land Configuration (Aspect):<\/strong> Influences local insolation but has less impact.<\/li>\n<\/ol>\n\n\n\n

    The Earth\u2019s axis, tilted at 66\u00bd\u00b0 to its orbital plane, significantly affects insolation distribution across latitudes.<\/p>\n\n\n\n

    Spatial Distribution of Insolation<\/h2>\n\n\n\n

    Insolation varies from 320 Watt\/m\u00b2 in the tropics to 70 Watt\/m\u00b2 at the poles. Maximum insolation occurs over subtropical deserts with minimal cloudiness. The equator receives less insolation than the tropics. At the same latitude, continents receive more insolation than oceans. In winter, middle and higher latitudes receive less radiation than in summer.<\/p>\n\n\n\n

    Heating and Cooling of the Atmosphere<\/h2>\n\n\n\n

    The atmosphere is heated and cooled through several processes:<\/p>\n\n\n\n

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    1. Conduction:<\/strong> Heat transfers from the warmed Earth\u2019s surface to the lower atmospheric layers in contact with it. This occurs when bodies of unequal temperature are in contact until they reach the same temperature or contact is broken.<\/li>\n\n\n\n
    2. Convection:<\/strong> Heated air rises vertically as currents, transferring heat to higher atmospheric layers. This is confined to the troposphere.<\/li>\n\n\n\n
    3. Advection:<\/strong> Horizontal movement of air transfers heat. It significantly affects daily weather variations in middle latitudes and causes local winds like the \u2018loo\u2019 in northern India during summer.<\/li>\n\n\n\n
    4. Terrestrial Radiation:<\/strong> The Earth, heated by insolation, radiates energy back in longwave form, heating the atmosphere from below. Greenhouse gases like carbon dioxide absorb this radiation, indirectly warming the atmosphere. The atmosphere then radiates heat back to space, maintaining a constant temperature.<\/li>\n<\/ol>\n\n\n\n

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