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Atmospheric circulation is the large-scale movement of air through the troposphere, and the means (with ocean circulation) by which heat is distributed around Earth. The large-scale structure of the atmospheric circulation varies from year to year, but the basic structure remains fairly constant because it is determined by Earth's rotation rate ...
Gallium does not exist as a free element in the Earth's crust, and the few high-content minerals, such as gallite (CuGaS 2), are too rare to serve as a primary source. [55] The abundance in the Earth's crust is approximately 16.9 ppm. It is the 34th most abundant element in the crust. [56]
With this addition the system of elements was extended to five and later commentators started referring to the new first one as the fifth and also called it aether, a word that Aristotle had used in On the Heavens and the Meteorology. [10] Aether differed from the four terrestrial elements; it was incapable of motion of quality or motion of ...
The most widely accepted theory of the Moon's origin, the giant-impact hypothesis, states that it formed from the collision of a Mars-size protoplanet called Theia with the early Earth. This hypothesis explains the Moon's relative lack of iron and volatile elements and the fact that its composition is nearly identical to that of Earth's crust. [40]
The abundance of the chemical elements is a measure of the occurrences of the chemical elements relative to all other elements in a given environment. Abundance is measured in one of three ways: by mass fraction (in commercial contexts often called weight fraction), by mole fraction (fraction of atoms by numerical count, or sometimes fraction of molecules in gases), or by volume fraction.
A proton is a stable subatomic particle, symbol p, H +, or 1 H + with a positive electric charge of +1 e (elementary charge).Its mass is slightly less than the mass of a neutron and approximately 1836 times the mass of an electron (the proton-to-electron mass ratio).
The fixed rate for a 15-year mortgage is 5.99%, up 28 basis points from last week's average 5.71%. These figures are lower than a year ago, when rates averaged 7.76% for a 30-year term and 7.03% ...
Oxygen is the third most abundant chemical element in the universe, after hydrogen and helium. [68] About 0.9% of the Sun's mass is oxygen. [19] Oxygen constitutes 49.2% of the Earth's crust by mass [69] as part of oxide compounds such as silicon dioxide and is the most abundant element by mass in the Earth's crust.