- 行业: Weather
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The American Meteorological Society promotes the development and dissemination of information and education on the atmospheric and related oceanic and hydrologic sciences and the advancement of their professional applications. Founded in 1919, AMS has a membership of more than 14,000 professionals, ...
The most widely used of all the indices of geomagnetic activity. It is intended as a measure of the worldwide (“p” is for planetary) average level of activity; however, it is very sensitive to certain auroral-zone activity and insensitive to some other types of disturbances. It is based on an index called the K index from each of 12 stations between latitudes 48° and 63°, selected for good longitudinal coverage. The Handbook of Geophysics and the Space Environment (1985) has a discussion of this and other geomagnetic indices.
Industry:Weather
The near-isotropic property exhibited by the high-frequency or finescale portion of otherwise nonisotropic turbulence that occurs at sufficiently large Reynolds numbers. See isotropic turbulence.
Industry:Weather
The most common of several names given to a significant decrease in sea surface temperature (“cold events”) in the central and eastern equatorial Pacific. La Niña is the counterpart to the El Niño “warm event,” and its spatial and temporal evolution in the equatorial Pacific is, to a considerable extent, the mirror image of El Niño, although La Niña events tend to be somewhat less regular in their behavior and duration. See also El Niño– Southern Oscillation.
Industry:Weather
The most recent time (15 000 to 80 000 years ago) during which continental glaciers covered subpolar regions and existed at elevations as much as 1000 m lower than today; corresponding to periods in which oxygen isotopes from marine sediment cores indicate that global sea level was 50–150 m lower and global temperature 5°–10°C lower than today.
Industry:Weather
The most recent time (115 000 to 125 000 years ago) during which global temperatures were as high as or higher than in the postglacial, when continental glaciers were limited to the Arctic and Antarctic, and sea levels were near current positions.
Industry:Weather
The Mach number of an isolated section of an airplane or its airframe, as contrasted with the free-stream Mach number.
Industry:Weather
The logarithm of any positive number n to the base b is the power l to which that base must be raised in order to satisfy the identity n = bl: l = logbn. Logarithms to the base 10 are called common logarithms and written log or log10. Logarithms to the base e = 2. 7182818284. . . Are called natural (Napierian, hyperbolic) logarithms, and are often written loge or ln. The natural logarithms are the more convenient in any computations involving differentiation.
Industry:Weather
The mean value of observations taken along a straight or curved line, such as along a highway or along an aircraft track. See average, ensemble average, area average, time average, ergodic condition.
Industry:Weather
The mean time for an air parcel to be displaced from one location to another.
Industry:Weather
