Vertical air motions increase ice formation in mixed-phase clouds. This correlation was predicted theoretically for a long time, but could now be observed for the first time in nature. This result was published by a team from Leibniz Institute for Tropospheric Research (TROPOS) in Leipzig in npj Climate and Atmospheric Science, an Open Access journal published by Nature Research. Using laser and radar equipment, the team measured the vertical air velocity and ice formation in thin mixed-phase clouds. Such clouds contain ice particles, water vapour as well as supercooled liquid droplets.
The results from Leipzig could help to map an important part of the water cycle better in the weather and climate models in the future by ice formation in clouds.
The formation of ice in clouds is a core element of the water cycle on Earth. It is usually difficult to isolate the ice formation process in order to study it individually because the interaction of aerosol particles, air motion and microphysical processes in clouds is too complex. Nevertheless, it is necessary to understand these processes in detail in order to better map this mechanism in weather and climate models.
The cloud researchers concentrated on a less spectacular and therefore less considered form of clouds in order to exclude other processes than primary ice formation. They investigated large cloud fields at an altitude of about 2 to 8 kilometres with a vertical extent of only 100 to 200 metres and contained extremely little ice in the range of micrograms per cubic meter.
Such thin cloudsallow both ice to be detected with a cloud radar and the vertical air movement with a Doppler lidar, as the laser beam can still penetrate the clouds. Both lidar and radar instruments were therefore necessary to investigate the turbulence and ice formation in these clouds above Leipzig from the ground.
"The effect only became visible when we observed the ice directly below the clouds’ top layer. Our findings enable for the first time quantitative and well constraint insights into the relationship between turbulence and ice formation in the atmosphere. The stronger a cloud is 'shaken' by vertical air motions, the more ice falls out of it," reports Dr Johannes Bühl of TROPOS.
This correlation was measured for clouds colder than -12 °C. Next, the remote sensing scientists want to explore the influence of aerosols by taking a closer look at the beginning (ice nucleation) and end (precipitation of ice particles) of the ice formation process.
Ice formation in clouds is an important process in the atmosphere, because without this ice practically no precipitation would fall from clouds in the middle latitudes of the Earth. As far-reaching as these processes may be, many details have not yet been sufficiently understood and are therefore not taken into account in the weather and climate models. Tilo Arnhold
The Leipzig Aerosol and Cloud Remote Observations System LACROS
Current data from LACROS:
Dr Johannes Bühl, Dr Patric Seifert, Dr Ronny Engelmann
Scientific staff, Department „Remote Sensing of Atmospheric Processes“ at the Leibniz Institute for Tropospheric Research (TROPOS), Leipzig, Germany
Phone +49-341-2717-7312, -7080, -7315
Dr Albert Ansmann
Leader of the Working Group Ground Based Remote Sensing, Department „Remote Sensing of Atmospheric Processes“ at the Leibniz Institute for Tropospheric Research (TROPOS), Leipzig, Germany
Public Relations at the Leibniz Institute for Tropospheric Research (TROPOS), Leipzig, Germany
Bühl, Johannes; Seifert, Patric; Engelmann, Ronny and Ansmann, Albert (2019): Impact of vertical air motions on ice formation rate in mixed-phase cloud layers. npj Climate and Atmospheric Science volume 2, Article number: 36 (2019). DOI: 10.1038/s41612-019-0092-6.
The study was funded by the European Union under the Seventh Framework Programme (ACTRIS / 262254 and BACCHUS / 603445) and the German Research Foundation (DFG; UNDINE / 162311106).
Tilo Arnhold | Leibniz-Institut für Troposphärenforschung e. V.
Manganese nodules: project on environmental impact during deep sea mining
08.11.2019 | Jacobs University Bremen gGmbH
Is the Baltic Sea at a crossroads?
05.11.2019 | Leibniz-Institut für Ostseeforschung Warnemünde
In two experiments performed at the free-electron laser FLASH in Hamburg a cooperation led by physicists from the Heidelberg Max Planck Institute for Nuclear physics (MPIK) demonstrated strongly-driven nonlinear interaction of ultrashort extreme-ultraviolet (XUV) laser pulses with atoms and ions. The powerful excitation of an electron pair in helium was found to compete with the ultrafast decay, which temporarily may even lead to population inversion. Resonant transitions in doubly charged neon ions were shifted in energy, and observed by XUV-XUV pump-probe transient absorption spectroscopy.
An international team led by physicists from the MPIK reports on new results for efficient two-electron excitations in helium driven by strong and ultrashort...
An international research group has observed new quantum properties on an artificial giant atom and has now published its results in the high-ranking journal Nature Physics. The quantum system under investigation apparently has a memory - a new finding that could be used to build a quantum computer.
The research group, consisting of German, Swedish and Indian scientists, has investigated an artificial quantum system and found new properties.
Researchers at the U.S. Department of Energy's (DOE) Argonne National Laboratory have reported a new mechanism to speed up the charging of lithium-ion...
Northwestern University chemists have used visible light and extremely tiny nanoparticles to quickly and simply make molecules that are of the same class as...
Almost everyone uses nanometer-sized alumina these days - this mineral, among others, constitutes the skeleton of modern catalytic converters in cars. Until now, the practical production of nanocorundum with a sufficiently high porosity has not been possible. The situation has changed radically with the presentation of a new method of nanocorundum production, developed as part of a German-Polish cooperation of scientists from Mülheim an der Ruhr and Cracow.
High temperatures and pressures, processes lasting for even dozens of days. Current methods of producing nanometer-sized alumina, a material of significant...
05.11.2019 | Event News
30.10.2019 | Event News
02.10.2019 | Event News
08.11.2019 | Earth Sciences
08.11.2019 | Earth Sciences
08.11.2019 | Trade Fair News