Although favorable conditions for tornadoes in the United States can occur at any time, they are most common in spring and least common in winter. Because spring is a transitional period for the climate, there are more chances of cooler air meeting with warmer air, resulting in more thunderstorms.
linear. 1  of or relating to a line or lines. 2  made of or using lines: linear design. 3  in relation to length only; extended in a line.  designating or of a style of art in which forms are sharply delineated and line is emphasized over color, light and shadow, etc.
1. (General Physics) the process of continual change in the physical position of an object; movement: linear motion. 2. (Physiology) a movement or action, esp of part of the human body; gesture. 3. (Physiology) a. the capacity for movement. b. a manner of movement, esp walking; gait.