Dispersion Conditions and Winds
The Dispersion Conditions and Winds map displays near-surface dispersion conditions as well as average winds at the 10-m (33 ft) level. There are six categories of dispersion conditions which are calculated by the Oklahoma Dispersion Model (ODM): Excellent (EX), Good (G), Moderately Good (MG), Moderately Poor (MP), Poor (P), and Very Poor (VP). The first three categories appear in various shades of green on the dispersion maps, while the last three range from beige to orange to red. A numbered system is also used to represent the six dispersion categories: 1=VP, 2=P, 3=MP, 4=MG, 5=G, and 6=EX. The ODM estimates near-surface dispersion, which is the ability of the atmosphere to dilute and disperse a compound such as smoke as it travels downwind. The calculated dispersion categories are valid for downwind distances of 1/4 mile to several miles. The categories can be interpreted as follows for a given downwind distance (e.g., 1 mile): the smoke concentration near the plume centerline will be greatest under VP conditions and the lowest under EX conditions. Thus, as a general guideline for prescribed burning, Moderately Good (MG) or better (G, EX) conditions should be present during the burn to avoid smoking out potential sensitive areas downwind. 10-m winds on this map are represented by wind vectors (arrows), whose lengths are proportional to the wind speed and which point in the direction toward which the wind is blowing. This map is updated every 5 minutes.