Question

what makes the isotherms run zigzag over Continental arises

Answer 1

Because of the small size of the earth compared to the sun and the great distance between the two (149 million kilometres), only a minute percentage of solar radiation—one in two billion parts—is intercepted by the earth.  But even this small amount of solar radiation reaching the earth is of great significance. All biological and many of the physical phenomena of the earth are controlled by this tiny proportion of solar radiation.