The axis of the Earth is tilted approximately 23.4° with respect to the orbital plane. Also, the surface of the Earth is curved. Due to this, the angle of incidence is not uniform everywhere on the Earth. Near the equator, the angle of incidence of the sun rays is almost 90° while near the poles, the sun rays fall obliquely on the land. As a result, large amount of heat is recieved by the equatorial region whereas the poles are cold throughout the year. The lesser the magnitude of the latitude of a place, the hotter it is. Thus, due to the difference in the angle of incidence of the sun rays on the surface of the earth, the temperature of land decreases as we move away from the equator and increases as we move toward the equator. The image gives a visual understanding of the concept.