Forces on sails to stay within the limitations of a craft's stability and power requirements, which are functions of hull (for boats) or chassis (for land craft) design. Sails derive power from wind that varies in time and with height above the surface. In order to do so, they are designed to adjust to the wind force for various points of sail. Both their design and method for control include means to match their lift and drag capabilities to the available apparent wind, by changing surface area, angle of attack, and curvature. Wind speed increases with height above the surface; at the same
MESO-SAILS SAILS many times: MESO-SAILS (Multiple Elevation Scan Option for SAILS). These additional supplemental low-level elevation scans are evenly spaced, in time (as close as possible given the defined VCP rotation rates), throughout the volume scan. The radar operator may choose 1 to 3 extra scans, depending on the weather situation. This lengthens the time of the total scan but provide low level coverage more often. During the Summer of 2013, the Radar Operations Center, in order to facilitate "Proof of Concept" testing of MESO-SAILS, defined two VCPs that were based on VCP-12 that included hardcoded additional low-level split-cut scans. For