5.8.1. Types of interactions

It is the process whereby incident radiation bounces-off the surface in a single predictable direction. Reflection is caused by the surfaces that are smooth relative to the wavelengths of incident radiation. As per Snell’s law, the angle of reflection is always equal and opposite to the angle of incidence. The amount of reflected energy will depend upon the material of the object, wavelength region, and the atmospheric condition.

Reflection occurs when light or electromagnetic radiation hits a surface and bounces back instead of being absorbed. For example, if you shine a flashlight on a mirror, the light reflects off in a specific direction, adhering to Snell’s law; the angle at which the light hits the mirror (angle of incidence) is the same as the angle at which it bounces away (angle of reflection). The effectiveness of this reflection depends on the smoothness of the surface and the type of material it’s made from, as well as environmental factors such as atmospheric conditions.

Think about water on a calm lake. When the sun shines on the lake, the light reflects off the water's surface, creating a beautiful mirror-like effect. If the water is disturbed by wind or rain, the reflection becomes distorted, showing that smooth surfaces lead to clearer reflections.

It is the process by which small particles diffuse a portion of the incident radiation in all directions. Scattering occurs when incident radiation is dispersed or spread out unpredictably in different directions. Scattering occurs with the surfaces that are rough relative to the wavelengths of incident radiation. Scattering of radiation by the constituent gases and aerosols in the atmosphere causes degradation of remotely sensed images. In the real world, scattering is much more common than the reflection. Scattering produces blurring of the objects in remotely sensed images, resulting in poor resolution. Three types of scattering commonly take place in the atmosphere: Rayleigh scattering, Mie scattering, and Non-selective scattering.

Scattering occurs when light interacts with small particles in the atmosphere, causing the light to spread out in many directions instead of traveling straight. This scattering can degrade the quality of images captured from remote sensing devices, making it often more difficult to distinguish features clearly. There are three primary types of scattering: Rayleigh scattering (caused by gases in the air, affecting shorter wavelengths like blue light), Mie scattering (caused by larger particles like dust), and non-selective scattering (which occurs with particles that are much larger than the wavelengths of light). Each of these types changes how we perceive colors in the atmosphere and how clear remote images are.

Imagine trying to see through foggy glasses. The tiny water droplets scatter the light, making everything look blurry. Similarly, when light travels through the atmosphere filled with gas or dust particles, it scatters, which can make satellite images of the Earth look unclear.

Three types of scattering commonly take place in the atmosphere: Rayleigh scattering, Mie scattering and Non-selective scattering. These will depend on the wavelength of incident radiant energy, and the size of gas molecule, dust particle, and/or water vapor droplet interacting with the EMR.

The types of scattering explain how light interacts with particles of different sizes in the atmosphere. Rayleigh scattering affects shorter wavelengths more strongly and is why the sky appears blue and sunsets appear reddish-orange, as shorter wavelengths scatter out and leave longer wavelengths to be seen. Mie scattering occurs with larger particles and affects all wavelengths somewhat equally, often giving the sky a whitish appearance. Non-selective scattering happens when particles are much larger than the wavelength of light, scattering all wavelengths together. This type of scattering often occurs in heavily polluted conditions, leading to a hazy appearance.

Think of a room with a fog machine. The light from a laser pointer looks different depending on the fog thickness. If the fog is dense (like in non-selective scattering), the light beams get spread out and lost. If it’s just a slight mist (like Rayleigh scattering), you see the beam clearly, but colors may shift due to scattering of shorter blue wavelengths.

--