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Scott Adamson
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Student in the Department of Meteorology at the University of Utah.
Some links of personal interest:
Rear-Flank Downdraft (Rough Draft)
A rear-flank downdraft (RFD) is a region of subsiding air located on the rear side of a mesocyclone in a supercell thunderstorm. Rear-flank downdrafts form on the rear side of the main updraft in a supercell thunderstorm, these downdrafts are often a broad region of subsiding air and are often associated with a hook echo.
Two processes can induce subsidence in a RFD: negative buoyancy and pressure perturbation. Negative buoyancy can be generated by diabatic cooling or precipitation loading. These downdrafts are due to negative buoyancy and downward CAPE causing subsidence. Precipitation loading also induces cooling driving a downdraft in addition to the rainshaft.
Vertical pressure perturbations are generated by the buildup of pressure due to the vertical buoyancy, creating a pressure perturbation gradient. Vertical perturbation pressure gradients can be generated by vertical gradients in pressure perturbations due to vertical buoyancy. The subsidizing air is generally dry and as it subsides the air warms adiabatically and can form a clearing in the cloud cover called a clear slot. A clear slot can be observed to wrap around a tornado or form away from a tornado in the shape of a horseshoe. This clearing is most likely the formation of the hook echo region associated with tornado formation. An RFD that originates in dry air and warms adiabatically can produce warmer observations out of the RFD at the surface.
The drag force from the droplets initiates circulation in a RFD. Dry environmental air is also entrained into the downdraft and evaporative cooling helps create more negatively buoyant air. As precipitation falls and cool entrained air circulated downward and eventually reaching the surface. This circulation contributes to the circulation to form a hook echo.
Sources
- Wallace and Hobbs, Atmospheric Science: An Introductory Survey 2006 pgs. 350-351
- Bluestein, Synoptic-Dynamic Meteorology in Midlatitudes Vol II 1993 pgs. 491, 493-495, 501
- Markowski, Hook Echoes and Rear-Flank Downdrafts: A Review Volume 130 2002 pgs. 852–876
Current Wikipedia information for Weather bombs
- Here is the link to the current Rear flank downdraft page.
Assignment #2 (part 6)
- A FA-class or featured article is an article which as been well written and received a peer review. This means that the article has valid information and requires no further editing.
- An A-class article is one that has met almost all requirements for the featured article status with the exception of missing a peer review.
- A GA-class or good article is one that need some more work to be nominated for featured class status. A good article provides sufficient information but could be better written for full clarification of the subject.
- A B-class article is one that needs completion to be considered a good article. Information is incomplete.
- A Start-class article is an article that may have some good information but lacking in many portions of the subject matter. the article must contain a useful graphic, multiple links about the subject matter, a subheading that completely talks about the one portion of the subject or multiple subheadings talking about what may be added to complete the article.
- A Stub-class article is an article that has little or no information needing a lot of work.
Proposal (part 7)
For my "wiki" project, I would like to elaborate on a rear flank downdraft. The page has a three sentence definition of what a weather bomb is. I would like to give this page some attention because it has a assessment rating of "Stub-class" article and I feel this subject is more mesoscale related.