Raindrop

What if a rainstorm dropped all of its water in a single giant drop?

What we know... a raindrop is simply some air moisture condensed ....

But....  How big can a raindrop be?

 Diameter and Weight

 Droplet sizes are measured in microns. 

 A micron is 1/1000 millimeter, or about 1/25,000 of an inch.

 A small changes in droplet diameter make big differences in droplet weight. 

An increase in droplet diameter from 150 microns to about 190 microns doubles the droplet weight. 

An increase in droplet diameter from 150 microns to about 240 microns increases the weight 4 times. Doubling the diameter to 300 microns increases its weight, and also its volume, by 8 times. 

Heavier droplets fall more quickly and are less affected by air movement.

Size and Number

When the size of spray droplets is reduced, their numbers increase, and the potential for drift also increases. Reducing droplet diameter in half multiplies the number of droplets by eight. 

Determination of Droplet Size and Number:-

 The Volume Median Diameter (VMD) refers to the midpoint droplet size (mean), where half of the volume of spray is in droplets smaller, and half of the volume is in droplets larger than the mean.

The American Society of Agricultural and Biological Engineers (ASABE) developed a droplet size classification system (ASABE S-572.1) that ranges from extra fine to ultra coarse based upon DV values measured in microns.

 The cloud liquid water content (LWC):- expressed either in g/m³ or g/kg

Convective clouds have a higher LWC than stratiform clouds. 

For convective clouds, the LWC increases with height (up to the level of glaciation) and it is higher when the cloud base temperature is higher. 

Maritime clouds generally have fewer but larger drops than continental drops, because there are fewer cloud condensation nuclei in the maritime troposphere

The LWC also depends on altitude in a cloud. 

Five possible zones can be distinguished within a deep-convective cloud, with glaciation in the topmost, an ice and droplet mixture in the next, then a 'rainout' layer, below which was a zone of rapid droplet growth by coalescence of droplets above 0° C, and then at the base a zone of very slow growth by diffusion (4). 'Rainout' occurs in a zone where the effective radius is stable at about 20-25 micron, and droplet growth by coalescence is balanced by loss of the larger droplets downwards.