X-BandA frequency band of microwave radiation in which radars operate.X-Ray BackgroundIn solar-terrestrial terms, 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 BurstIn solar-terrestrial terms, 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 ClassIn solar-terrestrial terms, rank of a flare based on its X-ray energy output. Flares are classified by the order of magnitude of the peak burst intensity (I) measured at the earth in the 1 to 8 angstrom band as follows:
Class | Intensity (in Watts/m2) |
B | I < 10-6 |
C | 10-6 <= I < 10-5 |
M | 10-5 <= I < 10-4 |
X | I >= 10-4 |
X-RaysVery energetic electromagnetic radiation with wavelengths intermediate between 0.01 and 10 nanometers (0.1-100 Angstroms) or between gamma rays and ultraviolet radiation. Essentially all X-Rays from space are absorbed in the Earth's upper atmosphere.
XBTExpendable Bathythermograph
XCITEDExcited
XCPTExpecting
XPCExpect
XSECCross Section