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.
Linear equation. A linear equation is an algebraic equation in which each term is either a constant or the product of a constant and (the first power of) a single variable (however, different variables may occur in different terms).