Fact Sheet - Mean Annual Temperature
Daily, climate stations in Kentucky record the highest and lowest temperature for a day. The mean daily temperature is the average of the highest and lowest temperature in a 24-hour period. The average of the twelve monthly average temperatures is the mean annual temperature. Thirty-year (1965-1994) averages of mean annual temperatures throughout Kentucky vary with a maximum of 60°F for Gilbertsville in the west and a minimum of 53.3°F for Ashland in the east.
Temperature is determined by the amount of solar radiation absorbed at the earth's surface. As the sun's angle from the zenith increases, the intensity of solar energy reaching the earth's surface decreases. The intensity weakens as the solar energy spreads out over a more expansive area on the surface. Increased sun angles from the zenith result in an increase for the distance traveled through the atmosphere of incoming solar radiation. Lengthening the distance traveled through the atmosphere weakens the intensity of solar radiation reaching the earths surface because of absorption and reflection from the atmosphere (Hartmann 1994). The effect in the middle latitudes is that the intensity of solar radiation reaching the earth's surface decreases northward. Kentucky is located in the middle latitudes and has a latitude range of more than two degrees.
Normally, temperature decreases with increasing height throughout the troposphere because the surface of the earth warms the air above it. As one rises, temperature decreases above the surface by 3.6°F per 1000 feet in altitude. The range of elevation in Kentucky is more than 3500 feet. The lower elevations are at the western edge of Kentucky with elevations of about 400 feet above mean sea level and, to the east, Black Mountain rises to 4,139 feet above mean sea level.
Temperature Rates of Change with Latitude and Elevation for Kentucky
Latitude and elevation influence mean annual temperatures in Kentucky. Temperature decreases by 1.8°F per degree increase in latitude because of variations in the sun's angle of incidence. The rate of change in temperature with elevation in Kentucky is 2.5°F per 1000 feet because colder air temperatures of higher altitudes interact with surface temperatures at higher elevations.
Estimating Mean Annual Temperatures in Kentucky
Mean annual temperature in degrees Farrenheit at any location in Kentucky can be estimated with latitude (degrees/minutes) and elevation (feet above mean sea level).