international atomic time

American  

noun

1. a system of measuring time based on atomic clocks that measure the second as the basic unit of time in the International System of Units (SI). IAT

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International Atomic Time British  

noun

1.  TAI.  the scientific standard of time based on the SI unit, the second, used by means of atomic clocks and satellites to synchronize the time standards of the major nations

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Example Sentences

The astronomical time, called Universal Time, or UT1, has tended to fall a few clicks behind the atomic one, called International Atomic Time, or TAI.

From New York Times

It was devised as a way to align the international atomic time scale, in use since 1967 and derived from the vibration of cesium atoms, with the slightly slower time that Earth keeps as it rotates.

From New York Times

In the summer of 1972, the International Time Bureau for the first time added a leap second to try to resolve a difference between International Atomic Time and the less-precise solar time.

From Slate

BIPM, a subsidiary of the CGPM, is responsible for generating International Atomic Time, on which utc is based, from the results of 500 clocks distributed around the world.

From Nature

International atomic time — on which coordinated universal time, or UTC, is based — is currently calculated by averaging measurements from hundreds of atomic clocks.

From Nature