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<br /> <br />2.3.2 Site Specific Wind Fields <br /> <br />Wind fields near the site are complicated by local terrain features as <br />well as the regional scale of the Rocky Mountain barrier. However, two <br />distinct scales predominate: synaptic and local. On a snyoptic scale, above <br />the atmosphere's first three to five thousand feet, air flow is from the western <br />quadrant. The dominance of the prevailing westerlies depends upon t:he location <br />and strength of major storm activity patterns. Wind fields in the <_urface or <br />boundary layer are significantly influenced by local terrain. Local mountain- <br />valley flow is forced by three-dimensional variations in the local temperature <br />patterns. <br />The following qualitative discussion of the atmospheric conditions known <br /> to occur in a mountainous environment is presented in the context of the <br />• dispersion and diffusion of particulates and Radon - 222. The effects of <br />orographically and thermally induced turbulence upon dispersion and diffusion, <br />over what is commonly referred to as complex terrain are well documented. (See <br />Table 2.3-3) <br />The mixing characteristics of the atmosphere (i.e., horizont~31 and <br />vertical motions) over flat terrain are determined primarily by hori::ontal and <br />vertical temperature gradients and synoptic scale wind circulation patterns; <br />however, over complex terrain the compass orientation and vertical extent of <br />local topography exert an additional dominating influence. Differeni:ial <br />surface heating (i.e., west-facing slopes warmer than east-facing slopes), <br />which results in response to the compass orientation of local topography and <br />daytime insolation creates a three dimensional temperature gradient that <br />forces wind circulation and turbulence. <br /> <br />~_t ~ <br />