V
An anabatic wind which forms during the day by heating of the valley floor. As the ground becomes warmer than the surrounding atmosphere, the lower levels of air heat and rise, flowing up mountain slopes.
A test designed to detect flaws in the mechanical operation of tide gauge chart recorders.
A measurement is taken of the positive distance between a fixed point near the top of the gauge, down through the stilling well to water level.
The sum of this distance, which is a maximum at low tide, and the tide gauge reading should be constant through a full tidal cycle. The sum when plotted against the measured distance (with the latter plotted on the vertical axis) should therefore be a vertical line. Deviations from the straight line can be interpreted as faults such as backlash in the gauge mechanism or scaling error.
See dodge tide.
Gaseous form of a substance.
The difference between the amount of moisture in the air and how much moisture the air can hold when it is saturated.
One of many deviations in the Moon's orbit caused by changes in the solar gravitational potential during the course of orbit, which produces variational constituents. See also evection.
A clockwise shift in the wind direction.
Rain that evaporates before it reaches the ground.
A measure of the opacity of the atmosphere. It is the greatest distance one can see prominent objects with unaided normal eyesight.
Rules that govern civil aircraft flight under conditions that allow navigation by visual reference to the earth’s surface.
Rotating mass of air or water, such as a tropical cyclone.
Measure of local rotation or spin in the atmosphere at a specified level. In weather analysis it usually refers to rotation around a vertical axis.