What are “short waves”? You occasionally refer to them.
—Frank Stachyra, Oak Park
A short wave goes by several slang names (upper level disturbance, upper level energy, pocket of cold air aloft, etc.), but it is a wave, aloft (say at 500 millibars), with a length of less than 3,700 miles. Short waves move downstream (usually eastward) an average of about 23 mph in the summer and 35 mph in the winter. Waves of greater length are known as long waves. Long waves move relatively slowly but the air within them moves much faster, sometimes more than 100 mph. The number of long waves existing at a given time is usually four or five in the Northern Hemisphere, but the number of short waves embedded within them is considerably greater.