อภิธานศัพท์ฟิสิกส์ (อวกาศ)


อภิธานศัพท์ฟิสิกส์ (อวกาศ)
เลือกดูโดยใช้ดัชนีคำศัพท์

พิเศษ | A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | ทั้งหมด

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T

TYPE I, II, III, IV

See RADIO EMISSION

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.

V

VERY HIGH FREQUENCY (VHF)

That portion of the radio frequency spectrum from 30 to 300 MHz.

VERY LOW FREQUENCY (VLF)

That portion of the radio frequency spectrum from 3 to 30 kHz.

W

WHITE LIGHT (WL)

Sunlight integrated over the visible portion of the spec- trum (4000 - 7000 angstroms) so that all colors are blended to appear white to the eye.

WHITE LIGHT FLARE

A major FLARE in which small parts become visible in white light. Such flares are usually strong X-ray, radio, and particle emitters.

WOLF NUMBER

An historic term for SUNSPOT NUMBER. In 1849, R. Wolf of Zurich originated the general procedure for computing the sunspot number.

X

X-RAY BACKGROUND

A daily average background X-ray flux in the 1 to 8 angstrom range. It is a midday minimum designed to reduce the effects of FLAREs.

X-RAY BURST

A temporary enhancement of the X-ray emission of the sun. The time-intensity profile of soft X-ray bursts is similar to that of the H-ALPHA profile of an associated FLARE.

X-RAY FLARE CLASS

Rank of a FLARE based on its X-ray energy output. Flares are classified by the order of magnitude of the peak burst inten- sity (I) measured at the earth in the 1 to 8 angstrom band as follows: Class (in Watt/sq. Meter) B I less than (l.t.) 10.0E-06 C 10.0E-06 l.e.= I l.t.= 10.0E-05 M 10.0E-05 l.e.= I l.t.= 10.0E-04 X I g.e.= 10.0E-04

Z

ZURICH SUNSPOT CLASSIFICATION

A sunspot classification system that has been modified for SESC use.


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