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A typical raindrop is about 2 mm in diameter, a typical cloud droplet is on the order of 0.02 mm, and a typical cloud condensation nucleus is on the order of 0.0001 mm or 0.1 μm or greater in diameter. [1] The number of cloud condensation nuclei in the air can be measured at ranges between around 100 to 1000 per cm 3. [1]
The droplet concentration of a cloud is the number of water droplets in a volume of cloud, typically a cubic centimeter (Wallace, 2006). The formula for the droplet concentration is as follows. = / In this equation, N is the total number of water droplets in the volume, and V is the total volume of the cloud being measured.
the cloud IR emissivity, with values between 0 and 1, with a global average around 0.7; the effective cloud amount, the cloud amount weighted by the cloud IR emissivity, with a global average of 0.5; the cloud (visible) optical depth varies within a range of 4 and 10. the cloud water path for the liquid and solid (ice) phases of the cloud particles
Cloud droplets normally form on aerosol particles that serve as CCN. Increasing the number density of CCN can lead to formation of more cloud droplets with a smaller size. The increase in number density increases the optical depth of the cloud, which results in an increase in the cloud albedo making clouds appear whiter. Satellite imagery often ...
The Wegener–Bergeron–Findeisen process (after Alfred Wegener, Tor Bergeron and Walter Findeisen []), (or "cold-rain process") is a process of ice crystal growth that occurs in mixed phase clouds (containing a mixture of supercooled water and ice) in regions where the ambient vapor pressure falls between the saturation vapor pressure over water and the lower saturation vapor pressure over ice.
The nucleation process of water droplets/ice micro-crystals from water vapor reproduced in the CLOUD experiment and also directly observed in the Earth atmosphere do not only involve ions formation due to cosmic rays but also a range of complex chemical reactions with sulfuric acid, ammonia and organic compounds emitted in the air by human ...
Three processes account for the formation of drops: water vapor condensation, accumulation of small drops on large drops and collisions between sizes. According to the time spent in the cloud, the vertical movement in it and the ambient temperature, drops have a very varied history and a distribution of diameters from a few micrometers to a few ...
This means that wet deposition is gravitational, Brownian and/or turbulent coagulation with water droplets. Different types of wet deposition include: Below-cloud scavenging. This happens when falling rain droplets or snow particles collide with aerosol particles through Brownian diffusion, interception, impaction and turbulent diffusion.