Growth of a cloud or precipitation particle by the collision and union of a frozen particle with a super-cooled water drop.

An instrument for measuring the extinction coefficient in water.

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

An instrument which measures the rate of evapotranspiration. It consists of a vegetation soil tank so designed that all water added to the tank and all water left after evapotranspiration can be measured.

A thermoelectric thermometer used for measuring air temperature. The name is derived from the fact that the reference thermocouple is placed in an insulated bottle.

The group of bits which a computer processes as a unit; often, 8 bits.

The rising of cold water from the deeper areas of the ocean to the surface. This phenomena often occurs along the California coast during the spring and summer.

A balloon having a detachable tail which is released when the balloon has undergone a predetermined expansion. It thus serves to measure approximately the density of the atmosphere at the point of release.

Strong winds concentrated within a narrow band in the atmosphere. The jet stream often "steers" surface features such as front and low pressure systems.

Name given to the unit of pressure in the International System of Units (SI). Equal to 1 newton/meter2 or 0.01 millibar.

An instrument used for measuring the specific gravity of a liquid.

An effect noted primarily in wet snow conditions when snow clings to the sides of a precipitation gauge and gradually accumulates until the gauge orifice is capped with accumulated snow. This effect can be minimized by using large collectors, and wind scr ...

An instrument used to measure the water vapor content of the air.

Same as instrument shelter.

An instrument for measuring radiant energy. It consists of an ether differential thermometer with blackened bulbs. One of the bulbs is exposed to the unknown radiation and the other to a black body source whose temperature can be varied. Equality of radia ...

A strong wind characterized by a sudden onset, a duration on the order of minutes, and a rather sudden decrease in speed.

Abbreviation for precipitation-evaporation quotient.

An instrument used to indicate wind direction.

The temperature at which all three phases of a substance can exist in equilibrium. This temperature occurs at only one pressure. The triple-point of water is 273.16 K and is the basis of the Kelvin scale.

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