کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
9605449 | 44139 | 2005 | 10 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
T-dependent rate measurements of homogeneous ice nucleation in cloud droplets using a large atmospheric simulation chamber
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موضوعات مرتبط
مهندسی و علوم پایه
مهندسی شیمی
بیو مهندسی (مهندسی زیستی)
پیش نمایش صفحه اول مقاله

چکیده انگلیسی
The rates of photochemical reactions in the atmosphere depend on the optical properties and lifetimes of clouds. These are critically affected by the process of droplet freezing, because ice crystals can grow to large sizes at the expense of the metastable supercooled droplets, thereby initiating graupel formation and precipitation. The large evacuable and coolable aerosol chamber AIDA at Forschungszentrum Karlsruhe has been used to generate supercooled clouds under controlled conditions. Homogeneous freezing was detected below â35.5 °C, and nucleation rates J(T) were measured to about â37 °C. They vary between â¼106 cmâ3 sâ1 at the highest and â¼108 cmâ3 sâ1 at the lowest temperature, although the temperature dependence of the nucleation rate is not very well constrained by the measurements. The results agree within the combined error limits with recent literature data. Homogeneous ice nucleation, which sets a lower limit to cloud freezing temperatures when other nucleation mechanisms are inefficient in the atmosphere, is important in deep convective systems and in cirrus.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 176, Issues 1â3, 14 December 2005, Pages 208-217
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 176, Issues 1â3, 14 December 2005, Pages 208-217
نویسندگان
Stefan Benz, Khaled Megahed, Ottmar Möhler, Harald Saathoff, Robert Wagner, Ulrich Schurath,