That could be because of a northward migration of tornado occurrence to more rural areas of the central USA, scientists say. Scroll down that page to locate the section on climatology. Humidity is a measure of the amount of invisible water vapor in the air. At 68 F, a comfortable range of humidity is 40-70 percent. An Ask Jack FAQ on humidity also answers some of the more common humidity questions.
Earth orbits the sun in an ellipse, which has a shape similar to an egg.
The sun is not in the middle of the ellipse, so the average distance between the two changes during the year. Perhaps surprisingly, it's Earth's tilt that controls the change in seasons. Our Ask Jack FAQ on the seasons and the Earth's relationship to the sun offers more information on this subject. Based on average annual wind speed, the windiest city in the USA is Blue Hill, Mass., with a speed of 15.4 mph. Lubbock's average is 12.4 mph.