Wind Speed

The wind speed is the mean wind speed over the vertical distribution of a plume. However, usually the only wind

Distance from Source (m)

FIG. 5.8.6 Horizontal dispersion coefficient as a function of downwind distance from the source. (Reprinted from D.B. Turner, 1970, Workbook of atmospheric dispersion estimates (Revised), Office of Air Programs Pub. No. AP-26, Research Triangle Park, N.C.: U.S. EPA.)

Distance from Source (m)

FIG. 5.8.6 Horizontal dispersion coefficient as a function of downwind distance from the source. (Reprinted from D.B. Turner, 1970, Workbook of atmospheric dispersion estimates (Revised), Office of Air Programs Pub. No. AP-26, Research Triangle Park, N.C.: U.S. EPA.)

speed available is that monitored at ground-level meteorological stations. These stations record ambient atmospheric characteristics, usually at the 10-m level, and typically with lower wind speeds than those affecting the plume. These lower speeds are due to the friction caused by the surface as shown in Figure 5.8.9. Therefore, the wind speed power law must be used to convert near-surface wind speed data into a wind speed representative of the conditions at the effective plume height. The wind speed power law equation is as follows:

where u1 and z1 correspond to the wind speed and vertical height of the wind station, while u2 and z2 pertain to the characteristics at the upper elevation. This formula is empirical, with the exponent derived from observed data. The exponent (p) varies with the type of ambient weather conditions, generally increasing with stability and surface roughness (Irwin 1979). It can range from 0.1 for calm conditions to 0.4 for turbulent weather conditions. Table 5.8.2 shows exponents for various types of surface characteristics. Table 5.8.3 shows selected values for both ur ban and rural modes as used for the six stability categories in the industrial source complex (ISC3) models.

Renewable Energy 101

Renewable Energy 101

Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable. The usage of renewable energy sources is very important when considering the sustainability of the existing energy usage of the world. While there is currently an abundance of non-renewable energy sources, such as nuclear fuels, these energy sources are depleting. In addition to being a non-renewable supply, the non-renewable energy sources release emissions into the air, which has an adverse effect on the environment.

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