User:Nopperman1

Summary of Featured Articles and Good Articles

In order to become a featured article, you must obtain the little bronze star that would be placed in the upper right corner of the article page. When that bronze star is observed on the top right corner, then you know that it is a featured article. A featured article is one that shows the best that Wikipedia has to offer in that it is the end result (or polished as they call it) of a collaborative effort to create an article that gives the best information that is possible by the users that helped to contribute. It showcases what Wikipedia is all about and can be seen as an example for the rest of the articles.

As far as I can tell, on the WikiProject-Meteorlogy homepage, there is a scale in which the articles are being rated. With FA being the highest, A, then GA, B, Start, Stub, Current, and needed. By looking at the number of articles in each quality category, it looks like this project is really struggling with A and FA rated articles with most lying in the start and stub regions of quality.

WikiProject: Proposal

Currently I am considering doing my wiki project on the mesoscale phenomena of microburst winds. I have been fascinated with the way in which microburst winds have caused severe damage in a relatively small area. I am also intrigued by the outflow which has pure divergence characteristics that is also seen with some microbursts. Upon digging around Wikipedia, I found that there is an article that is written on microbursts, but it is not a large article and could have more information posted to it. Another alternative is to focus primarily on dry microbursts, an event which can be seen here in Utah and is one of the reasons I have interest in this subject. The internet has many sources of information relating to the subject and can be a valuable source of information. Seen below are just a couple of links in which I felt were reliable sources of information that I can pull from in order to contribute to the Microburst article found on Wikipedia. My contribution would focus on the why part of microbursts and not so much the what part. I would try to explain using the knowledge gained from my meteorology classes and especially my mesoscale/radar meteorology class to help explain what is happening and why it is happening when a microburst occurs. Microbursts can be extremely dangerous and have proven deadly in the past and I feel it is important that as much information as possible can be obtained on these powerful wind events.

Microburst
Microburst Handbook
University of Illinois
NCAR
NOAA
The Weather Doctor
Charles A. Doswell III Paper

WikiProject: Microbursts

The curl phase soon after an intense microburst impacted the surface

Definition
A microburst is an intense windshear. A small, very intense downdraft that descends to the ground resulting in a strong wind divergence (outflow of winds equal in all directions upon impact). The size of the event is typically less than 4 kilometers (2.5 miles) across. Microbursts are capable of producing tornado-strength winds with gusts as high as 75 m/s (168 MPH) causing significant damage. The life span of a microburst wind event is around 5-15 minutes.

Dry microburst schematic from NWS.

Dry Microburst
When rain falls below cloud base or is mixed with dry air, it begins to evaporate and this evaporation process cools the air. The cool air descends and accelerates as it approaches the ground. When the cool air approaches the ground, it spreads out in all directions and this divergence of the wind is the signature of the microburst.
Dry microbursts, produced by high based thunderstorms that generate little surface rainfall, occur in environments characterized by a thermodynamic profile exhibiting an inverted-V at thermal and moisture profile, as viewed on a Skew-T log-P thermodynamic diagram. (Wakimoto, 1985) developed a conceptual model (over the High Plains) of a dry microburst environment that comprised of three important variables: mid-level moisture, a deep and dry adiabatic lapse rate in the sub-cloud layer, and low surface relative humidity.

Wet microburst schematic from NWS.

Wet Microburst
Wet microbursts are downbursts accompanied by significant precipitation at the surface (Fujita, 1985) which are warmer than their environment (Wakimoto, 1998). These downbursts rely more on the drag of precipitation for downward acceleration of parcels than negative buoyancy which tend to drive "dry" microbursts. As a result, higher mixing ratios are necessary for these downbursts to form (hence the name "wet" microbursts). Melting of ice, particularly hail, appears to play an important role in downburst formation (Wakimoto and Bringi, 1988), especially in the lowest one kilometer above ground level (Proctor, 1989). These factors, among others, make forecasting wet microbursts a difficult task.

Characteristic	Dry Microburst	Wet Microburst
Location of Highest Probability	Midwest/West	Southeast
Precipitation	Little or none	Moderate or heavy
Cloud Bases	As high as 500 mb	Usually below 850 mb
Features below Cloud Base	Virga	Shafts of strong precipitation reaching the ground
Primary Catalyst	Evaporative cooling	Downward transport of higher momentum
Environment below Cloud Base	Deep dry layer/low relative humidity/dry adiabiatic lapse rate	Shallow dry layer/high relative humidity/moist adiabatic lapse rate
Surface Outflow Pattern	Omni-directional	Gusts of the direction of the mid-level wind

Process of Wet and Dry Microbursts



Simple, Easy Explanation
In the case of a wet microburst, the atmosphere is warm and humid in the lower levels and dry aloft. As a result, when thunderstorms develop, heavy rain is produced but some of the rain evaporates in the drier air aloft. As a result the air aloft is cooled thereby causing it to sink and spread out rapidly as it hits the ground. The result can be both strong damaging winds and heavy rainfall occurring in the same area. Wet downbursts can be identified visually by such features as a shelf cloud, while on radar they sometimes produce bow echoes.

In the case of a dry microburst, the atmosphere is warm but dry in the lower levels and moist aloft. Thus when showers and thunderstorms develop, most of the rain evaporates before reaching the ground.

Basic Physical Processes using Simplified Buoyancy Equations

Start by using the vertical momentum equation File:Microburstbuoyancyeqt1.gif. By decomposing the variables into a basic state and a perturbation, defining the basic states, and using the Ideal Gas Law (p = ρRT_v, then the equation can be written in the form File:Microburstbuoyancyeqt2.gif where B is used to denote buoyancy. Note that the virtual temperature correction usually is rather small and to a good approximation, it can be ignored when computing buoyancy. Finally, the effects of precipitation loading on the vertical motion are parameterized by including a term that decreases buoyancy as the liquid water mixing ratio (l) increases, leading to the final form of the parcel's momentum equation: File:Microburstbuoyancyeqt3.gif Microbursts: Wind Shear Problems for Airplanes!

Microburst schematic from NASA. Note the downward motion of the air until it hits ground level, then spreads outward in all directions. The wind regime in a microburst is completely opposite to a tornado.

Effect of wind shear of plane trajectory. Note how merely correcting for the initial gust front can have dire consequences.

Aftermath of a microburst wind event on July 15, 1997 at the Griffen - Spalding County Regional Airport in Georgia.

I wonder what happens when I begin to put text into this spot. Will it put it underneat the left image, or will it put it to the right of it and to the left of the right image? Onyl time will tell and I must type quicker in order for time to go by more quikcly so that I could tell! Interesting article isn't it? I would have to say it is by far the best thing I have ever put onto the internet. Right up there with my smiling goat picture on facebook!

File:Ulogo10.gif University of Utah -- Department of Meteorology

This user is a member of WikiProject Meteorology.