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| Essay:Rain termsRain: Precipitation, either in the form of drops larger than 0.02 inch (0.5 mm), or smaller drops, which in contrast to drizzle, are widely separated. The following table shows how rainfall intensity is determined:
Rainfall Intensity Rainfall Intensity Rate-of-fall in 6-minutes Rate-of-fall in one hour Visual Estimation Light less than 0.01 inch Up to 0.10 inch From scattered drops that, regardless of duration, do not completely wet an exposed surface up to a condition where individual drops are easily seen. Moderate 0.01 to 0.03 inches 0.11 to 0.30 inches From scattered drops that, regardless of duration, do not completely wet an exposed surface up to a condition where individual drops are easily seen. Heavy more than 0.03 inches more than 0.30 inch Rain seemingly falls in sheets; individual drops are not identifiable; heavy spray to the height of several inches is observed over hard surfaces.
Rainbow: An arc that exhibits in concentric bands the colors of the spectrum and is formed opposite the sun by refraction and reflection of the sun's rays in rain drops.
Rain Foot: Slang for a horizontal bulging near the surface in a precipitation shaft, forming a foot-shaped prominence. It is a visual indication of a wet microburst.
Rain-Free Base: - A dark, horizontal cloud base with no visible precipitation beneath it. It typically marks the location of the thunderstorm updraft. Tornadoes may develop from wall clouds attached to the rain-free base, or from the rain-free base itself - especially when the rain-free base is on the south or southwest side of the main precipitation area. Note that the rain-free base may not actually be rain free; hail or large rain drops may be falling. For this reason, updraft base is more accurate.
Rain Induced Fog: When warm rain falls through cooler air, water evaporates from the warm rain. It subsequently condenses in the cool air forming fog. Such fog can be quite dense. It generally will persist as long as the rain continues. Since temperature rises little during the day, there is little diurnal variation in rain induced fog. Improvement in visibility cannot be expected until the rain stops or moves out of the affected area.
Rain Shadow: Areas of the leeward side of a mountain or mountain range which often receive much less rain than the windward side.
Rain Shield: It is a solid or nearly solid area of rain that typically becomes heavier as one approaches the eye of the hurricane. The outer edge is well defined and its distance from the eye varies greatly from storm to storm. The wind, both sustained and peak gusts, keeps increasing as much as one moves through the rain shield toward the storm's eye. | ||||||||||