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The scale of dBZ values can be seen along the bottom of the image. dBZ is a logarithmic dimensionless technical unit used in radar.It is mostly used in weather radar, to compare the equivalent reflectivity factor (Z) of a remote object (in mm 6 per m 3) to the return of a droplet of rain with a diameter of 1 mm (1 mm 6 per m 3). [1]
Radar cross-section (RCS), denoted σ, also called radar signature, is a measure of how detectable an object is by radar. A larger RCS indicates that an object is more easily detected. [1] An object reflects a limited amount of radar energy back to the source. The factors that influence this include: [1] the material with which the target is made;
Radar multipath echoes from a target cause ghosts to appear. Clutter may also originate from multipath echoes from valid targets caused by ground reflection, atmospheric ducting or ionospheric reflection/refraction (e.g., Anomalous propagation). This clutter type is especially bothersome since it appears to move and behave like other normal ...
#1 the fuchsia colored region, visible on the composite image, is all but missing on the base reflectivity #2 and #3, show more rain supported by strong updrafts. The composite reflectivity is the maximum dBZ reflectivity from any of the reflectivity angles of the NEXRAD weather radar. In the Composite, the highest intensities amongst those ...
These factors vary with atmospheric composition, geographic location, and time (see position of the Sun). While directional-hemispherical reflectance factor is calculated for a single angle of incidence (i.e., for a given position of the Sun), albedo is the directional integration of reflectance over all solar angles in a given period.
Diagram of Lambertian diffuse reflection. The black arrow shows incident radiance, and the red arrows show the reflected radiant intensity in each direction. When viewed from various angles, the reflected radiant intensity and the apparent area of the surface both vary with the cosine of the viewing angle, so the reflected radiance (intensity per unit area) is the same from all viewing angles.
In a radar image, one can see only the energy that was reflected back towards the radar antenna. The radar moves along a flight path and the area illuminated by the radar, or footprint, is moved along the surface in a swath, building the image as it does so. [1] Digital radar images are composed of many dots.
where Q is the efficiency factor of scattering, which is defined as the ratio of the scattering cross-section and geometrical cross-section πa 2. The term p = 4πa( n − 1)/λ has as its physical meaning the phase delay of the wave passing through the centre of the sphere, where a is the sphere radius, n is the ratio of refractive indices ...