Cyclonic cleaners do not use filtration bags. Portable vacuum cleaners working on the cyclonic separation principle became popular in the 1990s. Vayu continued to steadily strengthen after intensifying into a cyclonic storm. CVA produces divergence as a result of how there is a loss of cyclonic vorticity. The remnants soon developed into Very Severe Cyclonic Storm Bulbul. No systems strengthened beyond cyclonic storm status. Overall, there was a total of seven depressions and four cyclonic storms. Shearwise updrafts are the most important factor in determining cyclonic growth and strength. The winter rainfall is sometimes associated with the cyclonic activities. The next day, it intensified into Cyclonic Storm Onil. On 19 December, it intensified into a cyclonic storm. The IMD upgraded the system to Cyclonic Storm Sidr early on November 12. This ranked the system as a modern-day super cyclonic storm. Air and powder streams are segregated using gravity or cyclonic separation. A system of equilibrium can then establish itself creating circular movement, or a cyclonic flow.