อาทิตย์, 9 พฤษภาคม 2021, 10:51AM
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อภิธานศัพท์: อภิธานศัพท์ฟิสิกส์ (อวกาศ)
U

U BURST

A fast radio burst spectrum of a FLARE. It has a U-shaped appear- ance in an intensity-vs.-frequency plot.

ULTRA HIGH FREQUENCY (UHF)

Those radio frequencies exceeding 300 MHz.

UMBRA

The dark core or cores (umbrae) in a SUNSPOT with PENUMBRA, or a sunspot lacking penumbra.

UNIVERSAL TIME (UT)

See COORDINATED UNIVERSAL TIME.

UNSETTLED

With regard to geomagnetic levels, a descriptive word speci- fically meaning that 8 is less than or equal to the Ap INDEX which is less than or equal to15.