What is Albedo?
Albedo is a measure used to determine how much radiation is reflected from a surface. It compares the quantity of radiation reflected from a surface with the amount of radiation that strikes it. This concept also refers to the amount of energy emitted by electromagnetic waves reflected in the source.
In astronomy, there are two types of Albedos, the Normal Albedo and the other is the Bond Albedo. The Normal Albedo is reflected from a surface where both directions (i.e., the illumination direction and the viewpoint are perpendicular). The Bond Albedo is the small part of the fragment of solar radiation reflected into space from the Earth’s surface.
Albedo is also used in astronomy to determine the imprecise size of objects in the solar system. Because asteroids gravitate to be small and distant, they become visible as points of light to astronomers. Consequently, astronomers cannot directly measure their size. Astronomers instead use the perceivable brightness, along with the object’s Albedo and distance from Earth, to evaluate the object’s size.
Albedo is an aggregate that indicates how successfully a material reflects solar radiation. Albedo is measured in decimals between 0 and 1. A value of 0 is said to be a perfect absorber that does not reflect any radiation. A value of 1 specifies the material that reflects all radiation or a perfect reflector.
What is Reflectance?
Reflectance is the correlation of the quantity of light leaving a target to the amount of light striking the target. Reflectance doesn’t describe the specific properties, It describes functions of frequency, the wavelength of light, polarization, etc.
Reflectance is the ratio of the reflected transmitted energy of a surface to the incident transmitted energy of the surface. Since the Reflectance is a ratio of fluxes, it is unitless.
Reflectance depends on the thickness of the substance and is used in the field of science and engineering. Reflectance is used in studying soil science to determine soil’s physical properties, including particle size and moisture content. It is also important in astronomy, as reflectance spectroscopy is the main method for understanding the nature and composition of planets and asteroids.
The portion of an electric field reflected at a boundary or crossing point is called the reflection coefficient. And in turn, links to reflectance. Fresnel’s equation is used to calculate the reflection coefficient. It can be a real or a complex number. The surface’s reflectivity is said to be always positive and when the object’s reflectance is seen as zero it shows that there won’t be any reflection of any electromagnetic Waves that hit or collide.
Difference Between Albedo and Reflectance
- Albedo is a measure used to determine how much radiation is reflected from a surface. whereas Reflectance is the ratio of the reflected transmitted energy of a surface to the incident transmitted energy of the surface.
- Albedo does not depend on the thickness of the medium. on the contrary, Reflectance depends upon the thickness of the substance.
- Albedo is used in describing the specific properties of planets, satellites, and asteroids. On the other hand, Reflectance doesn’t describe the specific properties, It describes functions of frequency, the wavelength of light, polarization, etc.
- Albedo is used in the field of astronomy, Geology whereas Reflectance is used in the field of science and engineering.
- Albedo is measured in decimal between 0 and 1. A value of 0 is said to be a perfect absorber that does not reflect any radiation. A value of 1 specifies the material that reflects all radiation, or a perfect reflector. where Reflectance is a ratio of fluxes, it is unitless.
Comparison Between Albedo and Reflection
| Parameters of Comparison | Albedo | Reflectance |
| Definition | Albedo is a measure used to determine how much radiation is reflected from a surface. | The correlation of the quantity of light leaving a target to the amount of light striking the target is known as Reflectance. |
| Properties | Albedo is used in describing the properties of planets, satellites, and asteroids. | Reflectance doesn’t describe the specific properties, It describes functions of frequency, the wavelength of light, polarization, etc. |
| Use | Albedo is used in the field of astronomy, Geology, etc. | Reflectance is used in the field of science and engineering. |
| Dependency | Albedo does not depend on the thickness of the medium. | Reflectance depends on the thickness of the substance. |
| Example | An example of Albedo is snow and ice, as they are non-reflective. | An example of Reflectance can be a microscope, which uses a mirror to reflect light. |