Agriculture, like any endeavor, is bombarded with numbers and statistics. Percentages, averages, normal, total, ratings, and a variety of other terms are constantly reported and analyzed. While they may be useful, their real value is only apparent if you understand where they come from and how they are determined. One short column can hardly describe all this with adequate perspective. So today, let’s start discussing weather data but first some definitions.
• Average or mean: constituting the result obtained by adding together several quantities and then dividing this total by the number of quantities. In English, we have four people, three earn $5,000 per year and one earns $85,000 per year. The average salary is $25,000. That number poorly reflects what each actually makes.
• Median: The middle value in a distribution, above and below which lie an equal number of values. In English, half the values of a group lie above this value and half below. An example: you have four values (1, 2, 4, and 7). The average is (1+2+4+7/4) is 3.5, however, the mean is 3.
• Range: This is simply the “spread” of the values under consideration. In the previous example the range is 7-1 or 6.
• Extremes: In weather they will provide the record high, low and perhaps peak wind, highest rainfall and so on. These will matter in next week’s column.
• Frost or freeze: when the temperature drops below 32 degrees Fahrenheit (0 degrees Celsius). This is different from the next definition.
• Hard or killing freeze: the occurrence of temperatures cold enough to kill all but the hardiest vegetation, especially the last such occurrence in spring and the first in fall, events that limit the agricultural growing season. There are two ways of looking at this. One is for native vegetation and the other for crop and landscape plants. Normally, it is thought of as temperatures several degrees below freezing for several hours. And what is a killing frost for one plant may not be for another.
• Growing season: the length of time from the last killing frost in the spring until the first killing frost in the fall.
• Drought: there isn’t one totally accepted definition of drought. A drought is a period of below-average precipitation in a given region, that may result in prolonged shortages in the water supply, whether atmospheric, surface water or ground water. Some define it as less than seventy-five percent of normal precipitation.
These definitions provide a basis for next week’s discussion. What is normal as we look at our weather.

Dr. Victor L. Martin is the agriculture instructor/coordinator for Barton Community College. He can be reached at 620-792-9207, ext. 207.