Shortwave (meteorology)
Encyclopedia
A shortwave or shortwave trough is an embedded kink in the trough
/ ridge
pattern. This is the opposite of longwaves
, which are responsible for synoptic scale
systems, although shortwaves may be contained within or found ahead of longwaves and range from the mesocale
to the synoptic scale. Shortwaves are most frequently caused by either a cold pool or an upper level front
.
(CAA), which influence temperature. Due to the way they curve the air that moves around them and the way air moves away from them, shortwaves produce positive curvature vorticity and positive shear vorticity, respectively. Ahead of a shortwave there is large-scale lift due to divergence from positive vorticity advection
(PVA). This lift often sparks precipitation
. In a capped environment
, the lift generated by a shortwave may cool the inversion layer through adiabatic cooling, allowing for deep, moist convection
.
Trough (meteorology)
A trough is an elongated region of relatively low atmospheric pressure, often associated with fronts.Unlike fronts, there is not a universal symbol for a trough on a weather chart. The weather charts in some countries or regions mark troughs by a line. In the United States, a trough may be marked...
/ ridge
Ridge (meteorology)
A ridge is an elongated region of relatively high atmospheric pressure, the opposite of a trough....
pattern. This is the opposite of longwaves
Rossby wave
Atmospheric Rossby waves are giant meanders in high-altitude winds that are a major influence on weather.They are not to be confused with oceanic Rossby waves, which move along the thermocline: that is, the boundary between the warm upper layer of the ocean and the cold deeper part of the...
, which are responsible for synoptic scale
Synoptic scale meteorology
The synoptic scale in meteorology is a horizontal length scale of the order of 1000 kilometres or more. This corresponds to a horizontal scale typical of mid-latitude depressions...
systems, although shortwaves may be contained within or found ahead of longwaves and range from the mesocale
Mesoscale meteorology
Mesoscale meteorology is the study of weather systems smaller than synoptic scale systems but larger than microscale and storm-scale cumulus systems. Horizontal dimensions generally range from around 5 kilometers to several hundred kilometers...
to the synoptic scale. Shortwaves are most frequently caused by either a cold pool or an upper level front
Weather front
A weather front is a boundary separating two masses of air of different densities, and is the principal cause of meteorological phenomena. In surface weather analyses, fronts are depicted using various colored lines and symbols, depending on the type of front...
.
Corresponding weather and effects
Shortwaves are often associated with warm (WAA) or cold air advectionAdvection
Advection, in chemistry, engineering and earth sciences, is a transport mechanism of a substance, or a conserved property, by a fluid, due to the fluid's bulk motion in a particular direction. An example of advection is the transport of pollutants or silt in a river. The motion of the water carries...
(CAA), which influence temperature. Due to the way they curve the air that moves around them and the way air moves away from them, shortwaves produce positive curvature vorticity and positive shear vorticity, respectively. Ahead of a shortwave there is large-scale lift due to divergence from positive vorticity advection
Positive vorticity advection
Positive vorticity advection, or PVA, is the result of more cyclonic values of vorticity advecting into lower values of vorticity. It is more generally referred to as "Cyclonic Vorticity Advection"...
(PVA). This lift often sparks precipitation
Precipitation (meteorology)
In meteorology, precipitation In meteorology, precipitation In meteorology, precipitation (also known as one of the classes of hydrometeors, which are atmospheric water phenomena is any product of the condensation of atmospheric water vapor that falls under gravity. The main forms of precipitation...
. In a capped environment
Convective inhibition
Convective inhibition is a numerical measure in meteorology that indicates the amount of energy that will prevent an air parcel from rising from the surface to the level of free convection....
, the lift generated by a shortwave may cool the inversion layer through adiabatic cooling, allowing for deep, moist convection
Atmospheric convection
Atmospheric convection is the result of a parcel-environment instability, or temperature difference, layer in the atmosphere. Different lapse rates within dry and moist air lead to instability. Mixing of air during the day which expands the height of the planetary boundary layer leads to...
.
External links
- What is a shortwave trough?. Haby's Hints.
- Shortwave Trough. NWSNational Weather ServiceThe National Weather Service , once known as the Weather Bureau, is one of the six scientific agencies that make up the National Oceanic and Atmospheric Administration of the United States government...
Glossary.