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The Earth's orbit varies between nearly circular and mildly elliptical (its eccentricity varies). When the orbit is more elongated, there is more variation in the distance between the Earth and the Sun, and in the amount of solar radiation, at different times in the year.
Orbital forcing is the effect on climate of slow changes in the tilt of the Earth's axis and shape of the Earth's orbit around the Sun (see Milankovitch cycles).These orbital changes modify the total amount of sunlight reaching the Earth by up to 25% at mid-latitudes (from 400 to 500 W/(m 2) at latitudes of 60 degrees).
The effect of obliquity variations may, in concert with precession, be amplified by orbital inclination. As the 100,000-year periodicity only dominates the climate of the past million years, there is insufficient information to separate the component frequencies of eccentricity using spectral analysis, making the reliable detection of significant longer-term trends more difficult, although the ...
By astronomical convention, the four seasons are determined by the solstices (the two points in the Earth's orbit of the maximum tilt of the Earth's axis, toward the Sun or away from the Sun) and the equinoxes (the two points in the Earth's orbit where the Earth's tilted axis and an imaginary line drawn from the Earth to the Sun are exactly ...
The Sun is the predominant source of energy input to the Earth's climate system. Other sources include geothermal energy from the Earth's core, tidal energy from the Moon and heat from the decay of radioactive compounds. Both long term variations in solar intensity are known to affect global climate. [62]
Human activities “are altering the fabric of our land and the air above which is warming the climate, intensifying both wet and dry extremes, and sending wind and rainfall patterns out of kilter ...
Friction effects—between the core and mantle and between the atmosphere and surface—can dissipate the Earth's rotational energy. These combined effects are expected to increase the length of the day by more than 1.5 hours over the next 250 million years, and to increase the obliquity by about a half degree. The distance to the Moon will ...
Earth formed around 4.54 billion years ago [2] [3] [4] by accretion from the solar nebula. Volcanic outgassing probably created the primordial atmosphere, which contained almost no oxygen and would have been toxic to humans and most modern life. Much of the Earth was molten because of frequent collisions with other bodies which led to extreme ...