The boundary between the troposphere and stratosphere, usually characterized by an abrupt change in lapse rate. Its height varies from 10 to 20 km. Regions above the tropopause have greater atmospheric stability than regions below.

The ratios, to the mean wind speed, of the average magnitudes of the component fluctuations of the wind along three mutually perpendicular axes.

Wind with a speed between 4 and 6 knots (4 and 7 mph), Beaufort scale number 2.

The maximum distance, usually horizontally, at which a given object or light source is just visible under particular conditions of transmittance and background luminance.

The older name for the Celsius temperature scale. Officially abandoned by international agreement in 1948, but still in common use.

A defective maximum thermometer of the liquid-inglass type in which the mercury flows too freely through the constriction. Such a thermometer will indicate a maximum temperature that is too low.

The direction, with respect to true north, from which the wind is blowing. Distinguish from magnetic wind direction. In all standard upper-air and surface weather observations, it is true wind direction that is reported.

The sum of solar and terrestrial radiation.

Temperature of equilibrium between the liquid and vapor phases of a substance at a given pressure.

The atmospheric pressure at the level of the barometer. May or may not be the same as station pressure.

An Instrument used to determine dew point.

The mass density of a parcel of air expressed in units of mass per volume.

The ratio of the amount of electromagnetic radiation reflected by a body to the amount incipient upon it, commonly expressed as a percentage. The albedo is to be distinguished from the reflectivity, which refers to one specific wavelength.

That portion of the record of a microbarograph between any two (or a specified small number) of successive crossings of the average pressure level (in the same direction). Analogous to microseism.

An instrument which determines the altitude of an object with respect to a fixed level. There are two general types of altimeters: (a) the pressure altimeter, which gives an approximate measure of altitude from a pressure measurement and an assumed standa ...

A line of equal or constant pressure.

Sir Napier Shaw's name for the approximate absolute temperature scale,

In folklore, a name for rain.

Same as aneroid barometer. Holostelic means wholly made of solids, while aneroid means devoid of liquid.

Wind with a speed below 1 knot (1 mph); Beaufort scale number 0.