Precision
by Marcia Lee Jones
Title
Precision
Artist
Marcia Lee Jones
Medium
Photograph - Photography
Description
There are three main agents of vertical lift. One comprises two closely related processes which work together. Frontal lift and cyclonic lift occur when stable or slightly unstable air, which has been subjected to little or no surface heating, is forced aloft at weather fronts and around centers of low pressure.[3] Cloud droplets form when the air is lifted beyond the condensation level where water vapor condenses on so-called nuclei; (small particles) that grow to a size of typically 0.002 mm (.00008 in).[4] In a cloud the droplets collide to form larger droplets. These larger droplets remain aloft as long as the drag force of the air dominates over the gravitational force for small particles. If the cloud droplets continue to grow past this size, they become too heavy to be held aloft as the gravitational force overcomes the atmospheric drag, and they fall from the cloud as rain.[5] When this process takes place just above the freezing level, the vapor tends to condense into supercooled water droplets, which with additional lifting and growth in size, can eventually turn into freezing rain. At temperatures well below freezing, the vapor desublimates into ice crystals that average about 0.25 mm in length.[6] Continuing lift and desublimation will tend to increase the number of ice crystals which may combine until they are too heavy to be supported by the vertical air currents and fall out as snow.
Uploaded
March 19th, 2014
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