SHORTWAVES Typically in reference to a shortwave trough, it is a progressive disturbance (visualize a small, fast moving ripple on water) in the upper-levels of the atmosphere. Contrast with longwave. Given adequate moisture, rising air and resultant clouds and precipitation typically occurs ahead of shortwave troughs, while sinking air and drying conditions typically occur behind them. Shortwave troughs are always accompanied by a jet streak. Often used interchangeably with wave or disturbance. Shortwave can also be used to denote a shortwave ridge. Opposite to shortwave troughs, rising air and associated clouds and possible precipitation typically occur behind shortwave ridges (given adequate moisture), while sinking air and drying conditions typically occur ahead of them.

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