Environmental Factors

Our globe circles the Sun and one orbit takes a year. In addition, the Earth spins on its own axis once in 24 h and the rotation axis tilts 23.5° from the perpendicular to the Earth-Sun plane (Fig. 3.1.1). This geometry generates a strong annual cycle, especially at high latitudes. The distance between the globe and the Sun varies but is of lesser importance for the climate on the globe. On the other hand, the tilting of the rotation axis is the major factor in generating the annual cycle in the climate, a cycle that is particularly strong in the boreal zone. In summer, the day is very long; beyond the Arctic Circle we have polar day and the Sun does not set daily. The radiation energy input effects temperature variation. In winter, the days are short and beyond the polar circle we have polar night without daily sun rise.

The energy input at the top of the atmosphere depends on the variation of solar radiation and the position of the Earth in the solar system, as well as the angle of the Earth’s axis with respect to the ecliptic plane. The factors related to position and orientation of the Earth affect the climate system also via gravitational influence by the Sun and other planets of the solar system.