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In solar physics, a spicule, also known as a fibril or mottle, [a] is a dynamic jet of plasma in the Sun's chromosphere about 300 km in diameter. [1] They move upwards with speeds between 15 and 110 km/s from the photosphere and last a few minutes each [ 1 ] before falling back to the solar atmosphere. [ 2 ]
Under this scenario, they claimed the Sun might have contributed 50% of the observed global warming since 1900. [49] Stott et al. estimated that the residual effects of the prolonged high solar activity during the last 30 years account for between 16% and 36% of warming from 1950 to 1999. [50]
[nb 1] Earth's orbital speed averages 29.78 km/s (19 mi/s; 107,208 km/h; 66,616 mph), which is fast enough to cover the planet's diameter in 7 minutes and the distance to the Moon in 4 hours. [3] The point towards which the Earth in its solar orbit is directed at any given instant is known as the "apex of the Earth's way".
The Sun is classed as a G2 star, [66] meaning it is a G-type star, with 2 indicating its surface temperature is in the second range of the G class. The solar constant is the amount of power that the Sun deposits per unit area that is directly exposed to sunlight.
The ultraviolet radiation in sunlight has both positive and negative health effects, as it is both a requisite for vitamin D 3 synthesis and a mutagen. Sunlight takes about 8.3 minutes to reach Earth from the surface of the Sun. [ 3 ] A photon starting at the center of the Sun and changing direction every time it encounters a charged particle ...
The angular diameter of the Earth as seen from the Sun is approximately 1/11,700 radians (about 18 arcseconds), meaning the solid angle of the Earth as seen from the Sun is approximately 1/175,000,000 of a steradian. Thus the Sun emits about 2.2 billion times the amount of radiation that is caught by Earth, in other words about 3.846×10 26 watts.
On a prograde planet like the Earth, the sidereal day is shorter than the solar day. At time 1, the Sun and a certain distant star are both overhead. At time 2, the planet has rotated 360° and the distant star is overhead again (1→2 = one sidereal day). But it is not until a little later, at time 3, that the Sun is overhead again (1→3 = one solar day). More simply, 1→2 is a complete ...
When 1361 W/m 2 is arriving above the atmosphere (when the Sun is at the zenith in a cloudless sky), direct sun is about 1050 W/m 2, and global radiation on a horizontal surface at ground level is about 1120 W/m 2. [35] The latter figure includes radiation scattered or reemitted by the atmosphere and surroundings.