Dear Tom,
Your use of "normal temperatures" and "average temperatures" is confusing. Wouldn't "seasonal" be better than "normal"?
Jim Hurley, Glenview, Ill.
Dear Jim,
Seasonal temperatures refer to readings that occur commonly during a particular season, such as during the spring. The term does not have a precise definition in the atmospheric sciences. Meteorologists define "average" and "normal" in ways that are somewhat different from standard usage, and that is an unfortunate source of confusion.
In the atmospheric sciences, an average (such as an average temperature) is just what you think it is -- the sum of all the values in a set divided by the number of values. A normal is different. It is the specific average over a standard 30-year period, currently 1971-2000. For example, a normal temperature is the average temperature over the 30-year period from 1971 through 2000.
Your use of "normal temperatures" and "average temperatures" is confusing. Wouldn't "seasonal" be better than "normal"?
Jim Hurley, Glenview, Ill.
Dear Jim,
Seasonal temperatures refer to readings that occur commonly during a particular season, such as during the spring. The term does not have a precise definition in the atmospheric sciences. Meteorologists define "average" and "normal" in ways that are somewhat different from standard usage, and that is an unfortunate source of confusion.
In the atmospheric sciences, an average (such as an average temperature) is just what you think it is -- the sum of all the values in a set divided by the number of values. A normal is different. It is the specific average over a standard 30-year period, currently 1971-2000. For example, a normal temperature is the average temperature over the 30-year period from 1971 through 2000.
