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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]
Because of the greenhouse effect, the Earth's actual average surface temperature is about 288 K (15 °C; 59 °F), which is higher than the 255 K (−18 °C; −1 °F) effective temperature, and even higher than the 279 K (6 °C; 43 °F) temperature that a black body would have.
Consequently, such planets have surface temperatures higher than their effective radiation emission temperature. For example, Venus has an effective temperature of approximately 226 K (−47 °C; −53 °F), but a surface temperature of 740 K (467 °C; 872 °F).
The planets are solar thermal collectors on a large scale. The temperature of a planet's surface is determined by the balance between the heat absorbed by the planet from sunlight, heat emitted from its core, and thermal radiation emitted back into space. Emissivity of a planet is determined by the nature of its surface and atmosphere. [11]
The solution can also be expressed in terms of the effective emission temperature T e, which is the temperature that characterizes the outgoing infrared flux density F, as if the radiator were a perfect radiator obeying F=σT e 4. This is easy to conceptualize in the context of the model.
Death Valley is unbearably hot each year, but other spots on Earth are feeling the heat, too. And surface temperatures can be 50 degrees F hotter than the air. The Hottest Air Temperature on Earth ...
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
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