|Title||Mid-tropospheric supercooled liquid water observation consistent with nucleation induced by a mountain lee wave|
|Publication Type||Articolo su Rivista peer-reviewed|
|Year of Publication||2009|
|Authors||Madonna, F., Russo Felicita, Ware R., and Pappalardo G.|
|Journal||Geophysical Research Letters|
|Keywords||Artificial Neural Network, Atmospheric humidity, atmospheric moisture, Atmospherics, Boulder, Colorado, Cryogenic liquids, Ground level, Landforms, lee wave, Lee waves, Liquid water, Liquid water paths, Microwave devices, microwave radiometer, Microwave radiometer profilers, Microwave retrieval, Microwaves, Moisture, Neural network algorithm, Neural networks, North America, Nucleation, radiometry, Relative humidities, relative humidity, Sky condition, Supercooled droplets, Supercooled liquid water, Supercooling, Temperature and relative humidity, troposphere, twilight, Twilight zone, United States, USA, Vertical profile, Water analysis, Wave activity|
A case study relative to the observation of unexpected liquid water in an apparently cloudless atmosphere is presented. Microwave radiometer profiler observations on 14 April 2008 at Boulder, Colorado, USA, showed an increase in the liquid water path with values higher than 0.05 mm and corresponding relative humidity saturation from 4.75 to 6.75 km above the ground level in profiles retrieved using a neural network algorithm. The formation of small supercooled droplets identified in the microwave retrieval of the temperature and relative humidity vertical profiles may result from nucleation stimulated by a mountain lee wave. The presented analysis reveals the existence of supercooled liquid water in the mid troposphere related to a wave activity that occurred in a sky condition classifiable as "clear" and describes an atmospheric scenario consistent with the observation of the so-called twilight zone. Copyright 2009 by the American Geophysical Union.
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