- 行业: Weather
- Number of terms: 60695
- Number of blossaries: 0
- Company Profile:
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, ...
A hygrometer that measures relative humidity by means of the variation in length of a strand of human hair. The length variation of a properly treated hair is 2%–2. 5% when the humidity changes from 0%–100%. The hair hygrometer is considered to be a satisfactory instrument in situations where extreme and very low humidities are seldom or never found. The rate of response is very dependent on air temperature; the lag time increases with decreasing temperature. For air temperatures between 0° and 30°C and relative humidities between 20% and 80%, a good hair hygrometer should indicate 90% of a sudden change in humidity within about three minutes.
Industry:Weather
A halo in the form of a circle, or portion of a circle, with an angular radius of about 22° about a light source, such as the sun or moon. This is the most common of all halos. The sky is darker just to the inside of the halo than it is to the outside. The halo exhibits a pale coloration from a reddish tint on the inside fading to a bluish white on the outside. The 22° halo is explained by the refraction of light that enters one prism face and leaves by the second prism face beyond, thus being refracted by a prism with an effective angle of 60°. The angle of minimum deviation for an ice prism of this prism angle is about 22°, so such light does not appear inside the halo, accounting for the darker region there. The minimum angle of deviation varies slightly with wavelength, with the longer wavelengths being deviated least. This causes the reddish inner edge, outside which the additional contributions from light of increasingly shorter wavelengths decrease the color purity. The orientation that a crystal must have to contribute light to the halo depends on both the elevation angle of the light source and the portion of the halo in question, but the probability that a crystal will have a particular orientation depends upon its type and size. Consequently, it is frequently the case that for a given population of crystals and sun height, only a portion of the halo will be seen, while a change in one or the other might enable the full circle to form. It is not the case, despite being frequently asserted, that a view of the full circle requires crystals to have random orientations.
Industry:Weather
A historical halo candidate, of which no convincing photographic documentation is known. The possibility of this halo is based on early drawings of what seems to be a faint white halo of 90° radius centered on the sun. But good theoretical support is lacking, and subsequent reports seem to be misidentifications of the subhelic arcs.
Industry:Weather
A heave–pitch–roll sensor consisting of vertical acceleration and tilt sensors, used to measure the height and directionality of ocean surface gravity waves.
Industry:Weather
A halo in the form of a circle, or portion of a circle, with an angular radius of about 46° about a light source, such as the sun or moon. The coloration is reddish on the inner edge to bluish on the outer edge. This halo is much less common that the halo of 22°. The 46° halo is explained by the refraction of light passing through the 90° prism formed between the side and basal faces of a hexagonal ice crystal. The minimum angle of deviation for this ice prism is about 46°. Closely associated with this halo are the 46° infralateral arcs and the 46° supralateral arcs. In particular, the shape of the 46° supralateral arc often follows the uppermost parts of the 46° halo so closely that the two are almost impossible to distinguish. In fact, upon examination, a large fraction of the halos commonly interpreted as being 46° halos turn out to be pieces of 46° supralateral arcs. Which of the two halos (46° halo or 46° supralateral arc) is more frequent has not been settled.
Industry:Weather
A group of brominated organic compounds used as fire retardants, including CF3Br (halon 1301), CF2Br2 (halon 1202), CF2BrCl (halon 1211), and CF2BrCF2Br (halon 2402). The transport of these compounds to the stratosphere, followed by their photolysis to release Br atoms, gives this group a very high ozone depletion potential. The production of these compounds is now banned as a result of the Montreal Protocol and its subsequent amendments.
Industry:Weather
A graphical representation of a frequency distribution. The range of the variable is divided into class intervals for which the frequency of occurrence is represented by a rectangular column; the height of the column is proportional to the frequency of observations within the interval.
Industry:Weather
A glacier lying above a cliff or steep mountainside. As the glacier advances, its calving can cause ice avalanches.
Industry:Weather
A geometric and dynamic similarity that exists between two flow phenomena. In other words, in these two hydraulically similar situations, all homologous dimensions and homologous forces are in the same ratios.
Industry:Weather
A general term that refers to the collective hydraulic characteristics of a soil or rock such as the conductivity, permeability, water content, and pressure head, and the interrelationships among those properties.
Industry:Weather
