Skip to main content

Solar Radiation and Remote Sensing

Satellite Remote Sensing

Satellite remote sensing is the science of acquiring information about Earth's surface and atmosphere without physical contact, using sensors mounted on satellites. These sensors detect and record electromagnetic radiation (EMR) that is either emitted or reflected from the Earth's surface.

Solar Radiation & Earth's Energy Balance

  • Solar Radiation is the primary source of energy for Earth's climate system. It originates from the Sun and travels through space as electromagnetic waves.

  • Incoming Shortwave Solar Radiation (insolation) consists mostly of ultraviolet, visible, and near-infrared wavelengths. When it reaches Earth, it can be:

    • Absorbed by the atmosphere, clouds, or surface

    • Reflected back to space

    • Scattered by atmospheric particles

  • Outgoing Longwave Radiation is the infrared energy emitted by Earth back into space after absorbing solar energy. This process helps maintain Earth's thermal balance.

Electromagnetic Radiation (EMR) Spectrum

The EMR spectrum encompasses all types of electromagnetic radiation, ranging from gamma rays to radio waves. Remote sensing typically uses the visible, infrared, and microwave portions of the spectrum.

Different materials on Earth interact with different wavelengths in unique ways, which allows satellites to differentiate between water, vegetation, soil, urban areas, etc.

Interaction of EMR with Atmosphere and Surface

When solar radiation enters Earth's atmosphere and reaches the surface, it undergoes several interactions:

  • Absorption: Certain gases and materials absorb specific wavelengths of EMR, converting it into heat. For example, ozone absorbs UV, and water vapor absorbs infrared.

  • Scattering: Small particles and gases deflect radiation in multiple directions. Rayleigh scattering causes the blue sky, while Mie scattering is associated with dust and smoke.

  • Reflection: Some surfaces reflect incoming solar radiation back into the atmosphere. This reflection depends on the surface properties and is central to remote sensing.

  • Refraction: The bending of light as it passes through different media, affecting how radiation travels through the atmosphere.

Blackbody Concept & Earth

  • A Blackbody is an ideal object that absorbs all incoming radiation and re-emits it perfectly. Though Earth is not a perfect blackbody, the blackbody radiation laws (e.g., Planck's Law, Stefan–Boltzmann Law) help us understand Earth's emission of longwave radiation.

Albedo

  • Albedo is the fraction of incoming solar radiation that is reflected by a surface. Surfaces like snow have high albedo (high reflectivity), while forests or oceans have low albedo (high absorption).

    This directly influences Earth's energy budget and is monitored using satellite remote sensing to assess climate change, land cover changes, etc.

Conceptual Link Summary

  1. Solar Radiation from the Sun (mainly shortwave) enters Earth's atmosphere.

  2. It interacts with the atmosphere and surface via absorption, scattering, reflection, and refraction.

  3. Earth's surface emits longwave radiation, part of which escapes to space or is absorbed by greenhouse gases.

  4. These interactions are governed by principles of the EMR spectrum and concepts like blackbody radiation.

  5. Albedo quantifies the reflected portion of incoming solar energy.

  6. All these energy exchanges and surface properties are measured and monitored by satellite remote sensing.


Comments

Popular posts from this blog

Geology and Tectonic. Indian Shield

1. Ch (Chattisgarh Basin): Chattisgarh Basin is a geological region in central India known for its sedimentary rock formations. It's important for its mineral resources, including coal and iron ore. 2. CIS (Central Indian Shear Zone): CIS is a tectonic boundary in central India where the Indian Plate interacts with the Eurasian Plate. It's characterized by significant faulting and seismic activity. 3. GR (Godavari Rift): The Godavari Rift is a geological feature associated with the rifting and splitting of the Indian Plate. It's located in the Godavari River basin in southeastern India. 4. M (Madras Block): The Madras Block is a stable continental block in southern India. It's part of the Indian Plate and is not associated with active tectonic processes. 5. Mk (Malanjkhand): Malanjkhand is known for its copper deposits and is one of the largest copper mines in India. 6. MR (Mahanadi Rift): The Mahanadi Rift is a geological feature related to the rifting of the Indian Pl...

Neighbourhood Operations

 Neighbourhood Operations in GIS? In GIS and raster data , neighbourhood operations look at a group of nearby pixels (not just one) to understand or change a pixel's value. Think of it like checking what's around a house before deciding what color to paint it! Why "Neighbourhood"? Each pixel has " neighbours " (just like how your house has nearby houses). Neighbourhood operations check these nearby pixels and do some calculation to get a new value. 1. Aggregations (Summarizing Nearby Values) Aggregation means combining values of several pixels into one. We do this to: Find the average of surrounding pixels Find the minimum or maximum value Smooth the map (make it less rough) 🧒🏻 Example: Imagine checking the test scores of 9 students sitting around you and finding the average score . That's aggregation!  2. Filtering Techniques Filtering is used to improve or highlight features in a raster image, just like f...

Morpho-Tectonic Framework of India

The MorphoTectonic Framework of India refers to the combined study of the country's landforms (morphology) and its geological tectonic features. This framework provides insights into how geological forces have shaped India's topography over millions of years. Here's a breakdown of this concept: 1. Morphology: This aspect focuses on the physical features and landforms of India. It includes the study of mountains, plateaus, plains, valleys, rivers, and other surface features. For example, the Himalayas, Western Ghats, IndoGangetic Plains, and Deccan Plateau are prominent morphological features of India. 2. Tectonics: Tectonics deals with the movement and deformation of the Earth's lithosphere (the outermost rigid layer of the Earth). In the case of India, it primarily involves the interactions of the Indian Plate with neighboring tectonic plates. India is situated at the convergence of several major tectonic boundaries:     Collision with the Eurasian Plate: The most sign...

India – Geographic Location – Spatial Significance

India's geographic location holds immense spatial significance due to its position on the world map. Here's an explanation of India's geographic location and its spatial significance: Geographic Location: India is a vast South Asian country located on the Indian subcontinent. Its geographic coordinates are approximately between 8°4'N and 37°6'N latitude and 68°7'E and 97°25'E longitude. It is surrounded by several important bodies of water: - To the west, it has a coastline along the Arabian Sea. - To the east, it is bordered by the Bay of Bengal. - To the south, it faces the Indian Ocean. - To the north, India shares its land borders with Pakistan, China, Nepal, Bhutan, Bangladesh, and Myanmar. Spatial Significance: 1. Strategic Location: India's location places it at the crossroads of South Asia and the Indian Ocean region. This strategic position has made it historically important for trade, diplomacy, and geopolitics. 2. Trade and Commerce: India...