Factors Leading to the Formation of Arc Cloud Complexes.
Abstract
As a thunderstorm propagates past a station there is a rise and oscillation of the surface pressure. Downdrafts descending from thunderstorm cells are the source of air forming a cold dome over the ground which leads to a rise in surface pressure. If the cold downdrafts are strong enough and last for a sufficient time, an organized high pressure system develops at the surface, which is called a 'mesohigh'. In satellite imagery the leading edge of a mesohigh appears as an arc-shaped line of convective clouds moving out in all directions from a dissipating thunderstorm area. Twelve mesoscale convective systems (MCSs) were investigated. The duration of the gust front, produced by each MCS, was used to classify the MCSs. Category 1 MCSs were defined as ones that produced a gust front which lasted for more than 6 h; there were 7 category 1 MCSs in the sample. Category 2 MCSs were defined as ones that produced a gust front which lasted for 6 h or less; there were 4 category 2 MCSs. All the category 1 MCSs produced arc cloud complexes (ACCs), while only one of the category 2 MCSs produced an ACC. Composite analyses showed that Category 1 MCSs, on average, had higher thunderstorm heights, greater precipitation intensities, colder cloud top temperatures and produced larger magnitudes of surface divergence than category 2 MCSs.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1985
- Accession Number
- ADA166501
Entities
People
- Mark John Welshinger
Organizations
- Air Force Institute of Technology