Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Ice-phase clouds are the actual rainmakers

21.07.2015

New meteorological findings from Leipzig help to improve weather and climate predictions

New meteorological findings from Leipzig help to improve weather and climate predictions

Benjamin Franklin was the first to surmise that, even on a hot summer’s day, the raindrops falling on our heads might begin life as ice particles at high altitudes. In the centuries since 1780 it became possible to probe the atmosphere directly by balloon and by aircraft, and remotely from the ground and from satellites. These observations have confirmed Franklin’s suspicion. However, two questions remain: how large are the fractions of rain produced by liquid clouds and by ice clouds? And how variable are they over the globe and over time?

A new study accepted for publication in Geophysical Research Letters, a journal of the American Geophysical Union, gives us the answers. The new study confirms the prevalence of rain from ice clouds at mid-latitudes, and shows rain from ice clouds prevails to an astonishing extent, according to Johannes Mulmenstadt, a scientist at the Institute of Meteorology at Universitat Leipzig and the study’s lead author.

Over land outside the tropics, only one percent of rain events involve ice-free clouds, according to the new study. Even in the tropics, where rain from liquid clouds is more common, there is a remarkable contrast between rain events over land and ocean, according to Mulmenstadt.

The technological breakthrough that made the study possible is three satellites, designed and launched by NASA and its partners in Europe and Japan, that fly in close formation and provide a picture of the Earth’s atmosphere far clearer than any of the constellation’s individual components. Over the course of five years, the satellites, named Aqua, Calipso, and CloudSat, have taken snapshots of over 50 million raining clouds, which are made freely available to scientists worldwide. Among the instruments the satellites carry are a cloud radar that detects large raindrops and ice crystals; a powerful green laser beam and light detector sensitive to small liquid droplets and can distinguish between liquid and ice clouds; and a spectroradiometer that measures the reflection of sunlight from clouds and infers cloud properties like the total liquid and ice content and the size of cloud droplets or ice particles near the top of the cloud.

“Using the combined information from these satellites, we now know where on Earth rain falls from liquid clouds and where it falls from ice clouds, and the results are striking,” Mulmenstadt said.

The new findings may be a sign of human influence on the global water cycle, according to the study’s authors.

Liquid clouds tend to produce drizzle, while ice clouds produce more intense rain. Tiny particles referred to as “aerosols” that are suspended in the atmosphere may be able to influence clouds in their infancy and determine whether they grow into drizzling liquid clouds or intensely raining ice clouds. And these aerosols are more abundant over land, in part due to the combustion processes that power human activity, according to the study’s authors.

“There are many other differences between the marine and continental atmospheres, but one big one is aerosols. How much of a role they play—and whether the preindustrial atmosphere may indeed have seen more drizzle and less intense rainfall than the present day atmosphere—is the question we’ll be addressing next,” said Mulmenstadt.

“The results of this study are consistent with an aerosol effect: clouds over land have a bigger droplet size gap to overcome before they can begin to drizzle than clouds over the ocean. But that by itself is not yet enough to prove an aerosol influence.”

The study’s results also provide an observational crosscheck that may be useful for fine-tuning atmospheric models for weather and climate prediction. The portrait that these models paint of rain is less accurate than their representation of other processes. Frequency and intensity of rain in the models are especially troublesome, Mulmenstadt said.

“Checking whether models produce virtually all their rain over land from ice clouds, as our observations say they should, may be a fruitful way to attack this problem,” he said.

In light of the importance of rain for aspects of life from agriculture to transportation disruptions to widespread flood damage, this is an area in urgent need of continued research, Mulmenstadt added.

publication:
"Frequency of occurrence of rain from liquid-, mixed- and ice-phase clouds derived from A-Train satellite retrievals", Johannes Mülmenstädt, Odran Sourdeval, Julien Delanoë and Johannes Quaas, Geophysical Research Letters. Juli 2015. DOI: 10.1002/2015GL064604

further information:

Dr. Johannes Mülmenstädt
Leipzig Institute for Meteorology - LIM
phone: +49 341 97-32937
e-mail: johannes.muelmenstaedt@uni-leipzig.de
Web: http://www.uni-leipzig.de/~meteo/en/index.php

Weitere Informationen:

http://onlinelibrary.wiley.com/wol1/doi/10.1002/2015GL064604/abstract link to the publication

Katrin Henneberg | Universität Leipzig

Further reports about: Atmosphere Geophysical Research clouds ice clouds ice particles raindrops satellites

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

Researchers devise microreactor to study formation of methane hydrate

23.08.2017 | Materials Sciences

ShAPEing the future of magnesium car parts

23.08.2017 | Automotive Engineering

New insights into the world of trypanosomes

23.08.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>