User Tools

Site Tools

Please register and/or login to edit and create pages


start:earth_sciences:cloud_ice_formation

Wikenigma - an Encyclopedia of Unknowns Wikenigma - an Encyclopedia of the Unknown Wikenigma - an Encyclopaedia of Unknowns Wikenigma - an Encyclopaedia of the Unknown

Cloud ice formation

The formation of ice crystals have important implications for stratospheric ozone chemistry, cloud dynamics, rock weathering, and hydrate formation etc., however the exact mechanisms by which microscopic particulate matter 'seeds' ice-crystals are unknown. Atmospheric dust (clay dust etc) and microscopic organisms are known to seed clouds, but there is currently no explanation as to why some varieties are very effective and others are not. 1)

Cirrus clouds for example, which cover about 30% of the Earth’s surface, are formed from ice crystals, the majority of which have been seeded by a particle (in the process known as heterogeneous nucleation).

“Cirrus clouds play an important role in the radiative budget of the Earth. Due to scattering and absorption of the solar as well as terrestrial radiation the cirrus cloud cover may influence significantly the Earth climate. How the cirrus clouds exactly form, is still unknown.”

ETH Zurich, 2016

Further info:

“How aerosol particles act as nuclei for ice and other crystalline phases like hydrates, and how this can quantitatively be described in models, are among the major open questions in atmospheric cloud and climate research.”

Institute of Meteorology and Climate Research

Note: The question also arises in the formation of snow flakes, which are also often 'seeded' with microscopic particulate matter at their centre. Exactly how the particles facilitate the flakes to form is unknown.

                  importance rating for this page

    Share this page

1) The phenomenon is currently exploited in cloud seeding procedures to induce rainfall.

DOKUWIKI IMPLEMENTATION DESIGN BY UNIV.ORG.UK