Gravity waves form in the atmosphere as a result of destabilizing processes, for example at weather fronts, during storms or when air masses stroke over mountain ranges. They can occasionally be seen in the sky as bands of cloud. For weather forecast and climate models, however, they are mostly “invisible” due to their short wavelength. The effects of gravity waves can only be taken into consideration by including additional special components in the models. The “MS-GWaves” research unit funded by the German Research Foundation and led by Goethe University Frankfurt has meanwhile further developed such parameterizations and will test them in the second funding period.
Although gravity waves have comparatively short wavelengths of between just a few hundred metres and several hundred kilometres, at times they influence the transport of water vapour as well as large-scale winds and temperature distributions to a considerable degree. This effect is strongest in the upper layers of the atmosphere. These, in turn, have such a strong effect on the lower layers too that a realistic modelling of weather and climate in the atmosphere is impossible without giving due consideration to gravity waves. Gravity waves also play a significant role for air traffic in predicting turbulence and are an important factor in weather extremes, such as heavy rain or storms.
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Image Credit: Copyright Dr. Gerd Baumgarten