Ask Heather - terrain and weather

KNOXVILLE, Tenn. (WVLT) -- Weather patterns often change as they move in to our area, and Steven Neilsen wanted to know why the terrain of East Tennessee affects the weather.

Some basic Meteorology background first. The troposphere is the lowest layer of Earth's atmosphere, where all weather takes place. The troposphere starts at Earth's surface and goes up to a height of 23,000 to 65,000 feet.

Friction is a force that impacts the weather at the surface, by slowing motion and energy. Think of wind blowing through trees. The trees alter and impede the wind flow. So, rough terrain and elevation changes alter the wind speed can promote uplift, or cloud and storm development.

Say the the base of a thunderstorm is around 5,000 feet, that's above the surface elevation. In our area the surface elevation changes from one point in our area to the other.

Knoxville 886 feet (Valley)
Crossville 1,867 feet (Plateau)
Middlesboro, KY 1,155 feet (SE KY)
Black Mountain in Harlan County, KY 4,144 feet (SE KY Mountains)
Maryville 940 feet (Valley to foothills of Smokies)
Gatlinburg 1,289 feet (Smoky Mountains)
Clingmans Dome in the Smokies 6,643 feet

As a system moves from one elevation to the other, the conditions of that area will impact the changing weather pattern. In the areas with hundreds of miles of flat land, there isn't any major differences in the weather conditions before a front moves in to one area verses another. Meanwhile in East Tennessee and Eastern Kentucky, temperatures and wind speeds can vary greatly from one part of our area to another, feeding into and impacting an approaching system.

If you have a question about the weather, Ask Heather.

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