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Surface albedo is defined as the ratio of radiosity J e to the irradiance E e (flux per unit area) received by a surface. [2] The proportion reflected is not only determined by properties of the surface itself, but also by the spectral and angular distribution of solar radiation reaching the Earth's surface. [3]
Cloud albedo is a measure of the albedo or reflectivity of a cloud. Clouds regulate the amount of solar radiation absorbed by a planet and its solar surface irradiance . Generally, increased cloud cover correlates to a higher albedo and a lower absorption of solar energy .
The Earth has an albedo of 0.3, meaning that 30% of the solar radiation that hits the planet gets scattered back into space without absorption. The effect of albedo on temperature can be approximated by assuming that the energy absorbed is multiplied by 0.7, but that the planet still radiates as a black body (the latter by definition of ...
On the one hand, white cloud tops promote cooling of Earth's surface by reflecting shortwave radiation (visible and near infrared) from the Sun, diminishing the amount of solar radiation that is absorbed at the surface, enhancing the Earth's albedo. Most of the sunlight that reaches the ground is absorbed, warming the surface, which emits ...
The albedo of several types of roofs (lower values means higher temperatures). Reflective surfaces, or ground-based albedo modification (GBAM), is a solar radiation management method of enhancing Earth's albedo (the ability to reflect the visible, infrared, and ultraviolet wavelengths of the Sun, reducing heat transfer to the surface).
is Earth's average albedo, measured to be 0.3. [11] [12] is Earth's average surface temperature, measured as about 288 K as of year 2020 [13] is the effective emissivity of Earth's combined surface and atmosphere (including clouds). It is a quantity between 0 and 1 that is calculated from the equilibrium to be about 0.61.
Earth has an albedo of about 0.306 and a solar irradiance (L / 4 π D 2) of 1361 W m −2 at its mean orbital radius of 1.5×10 8 km. The calculation with ε=1 and remaining physical constants then gives an Earth effective temperature of 254 K (−19 °C). [11] The actual temperature of Earth's surface is an average 288 K (15 °C) as of 2020. [12]
Radiative forcing is defined in the IPCC Sixth Assessment Report as follows: "The change in the net, downward minus upward, radiative flux (expressed in W/m 2) due to a change in an external driver of climate change, such as a change in the concentration of carbon dioxide (CO 2), the concentration of volcanic aerosols or the output of the Sun." [3]: 2245