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 perspective - the appearance of things relative to one another as determined by their distance from the viewer. perspective. appearance, visual aspect - outward or visible aspect of a person or thing. vanishing point - the appearance of a point on the horizon at which parallel lines converge.