## Meteorology

### Balloon shroud

Same as balloon cover.

### Bandwidth

The number of cycles per second between the limits of a frequency band.

### Bankfull stage

The stage, on a fixed river gauge, corresponding to the top of the lowest banks within the reach for which the gauge is used as an index. Compare to flood stage.

### Bar

A unit of pressure equal to 10' dyne per cm-' (101 barye), 1000 millibars. 29.53 inches of mercury.

### Barogram

The record of a barograph.

### Barograph

A continuous-recording barometer.

### Barometer

An instrument for measuring the pressure of the atmosphere. The two principle types are aneroid and mercurial.

### Barometric pressure

Same as atmospheric pressure.

### Baroswitch

A pressure-operated switching device used in a radiosonde. In operation, the expansion of an aneroid capsule causes an electrical contact to scan a radiosonde commutator composed of conductors separated by insulators.

### Barothermograph

An instrument that automatically records pressure and temperature.

See river basin.

### Basin accounting

See hydrologic accounting.

### Basin Lag

A computed characteristic of a particular river basin, expressed as the time difference between the time-center of mass of rainfall and the time-center of mass of resulting runoff.

### Basin recharge

The difference between amounts of precipitation and runoff for a given storm. It is that portion of the precipitation that remains in the basin as soil moisture, surface storage, ground water, etc.

### Baud

A unit of signaling speed representing the number of code elements sent per second; often, bits per second.

### BCD

Binary Coded Decimal. A coding system in which each decimal digit from 0 to 9 is represented by a 4-digit binary number.

### Beaufort wind scale

A system of estimating and reporting wind speed, originally based on the effect of various wind speeds on the amount of canvas that a full-rigged nineteenth century frigate could carry.

### Bellani atmometer

An instrument which measures evaporation by measuring the loss of water from a burette reservoir through a ceramic disc.

### Bellows

See aneroid capsule.

### Bimetal strip

See bimetallic thermometer.