![]() This amount is called the absorbed solar radiation (ASR). Of the ~340 W/m 2 of solar radiation received by the Earth, an average of ~77 W/m 2 is reflected back to space by clouds and the atmosphere and ~23 W/m 2 is reflected by the surface albedo, leaving ~240 W/m 2 of solar energy input to the Earth's energy budget. Since the absorption varies with location as well as with diurnal, seasonal and annual variations, the numbers quoted are multi-year averages obtained from multiple satellite measurements. the area of a circle), the globally and yearly averaged TOA flux is one quarter of the solar constant and so is approximately 340 watts per square meter (W/m 2). Because the surface area of a sphere is four times the cross-sectional area of a sphere (i.e. The total amount of energy received per second at the top of Earth's atmosphere (TOA) is measured in watts and is given by the solar constant times the cross-sectional area of the Earth corresponded to the radiation. Incoming solar energy (shortwave radiation) In spite of the enormous transfers of energy into and from the Earth, it maintains a relatively constant temperature because, as a whole, there is little net gain or loss: Earth emits via atmospheric and terrestrial radiation (shifted to longer electromagnetic wavelengths) to space about the same amount of energy as it receives via solar insolation (all forms of electromagnetic radiation). Brightest white areas show the highest reflectivity (least absorption) of solar energy, while darkest blue areas show the greatest absorption. Accurate quantification of these energy flows and storage amounts is a requirement within most climate models.Įarth's energy flows Incoming, top-of-atmosphere (TOA) shortwave flux radiation, shows energy received from the Sun as inferred from CERES measurements (26–). This is due to the thermal inertia of the oceans, land and cryosphere. ![]() When the energy budget changes, there is a delay before average global surface temperature changes significantly. The rate of heating from this human-caused event is without precedent. Multiple types of measurements and observations show a warming imbalance since at least year 1970. Global warming occurs when earth receives more energy than it gives back to space, and global cooling takes place when the outgoing energy is greater. When the incoming and outgoing energy fluxes are in balance, Earth is in radiative equilibrium and the climate system will be relatively stable. The result is Earth's climate.Įarth's energy budget depends on many factors, such as atmospheric aerosols, greenhouse gases, the planet's surface albedo (reflectivity), clouds, vegetation, land use patterns, and more. As the energy seeks equilibrium across the planet, it drives interactions in Earth's climate system, i.e., Earth's water, ice, atmosphere, rocky crust, and all living things. Because the Sun heats the equatorial tropics more than the polar regions, received solar irradiance is unevenly distributed. The energy budget also accounts for how energy moves through the climate system. Smaller energy sources, such as Earth's internal heat, are taken into consideration, but make a tiny contribution compared to solar energy. Įarth's energy budget accounts for the balance between the energy that Earth receives from the Sun and the energy the Earth loses back into outer space. The imbalance (or rate of global heating shown in figure as the "net absorbed" amount) grew from +0.6 W/m 2 (2009 est. It is measured by satellites and shown in W/m 2. For Earth's internal heat, see Earth's internal heat budget.Įarth's climate is largely determined by the planet's energy budget, i.e., the balance of incoming and outgoing radiation. ![]() This article is about energy flows at and above Earth's surface.
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