Earth-Sun Relationships

Why are earth-sun relationships important in the study of physical geography?

Physical geology includes geomorphology which is the study of the origin of the modification of landforms via dynamic processes. It also includes sedimentology, which is the study of erosion and deposition of rock particles by way of ice, water or wind.

The earth-sun relationship truly dictates the weather, which in turn, has a direct impact on the aspects of the planets geology as show in the studies mentioned above. Of course physical geology also includes mineralogy, petrology, geochemistry, geophysics and economic geology, structural geology. Geophysics is the study of how rock materials behave in response to stresses according to physics. (Retrieved on 09/28/06 from source, N. Coch and A. Ludman, Physical Geology (3d ed. 1991)
I believe the weather may play a part in this study as well. Ice bergs may melt and redistribute weight and possibly strain areas of the earths crust. This would be caused by the earth-sun relationship in the axis tilt that may cause increased heat focused on areas of the earth that have become used to lower temperatures.

The earth’s rotation from west to east on its axis comprises a solar day. There are a set of physical consequences that are produced; among them are, the Coriolis Effect, tides, daily rhythm of light and heat, and the oblate ellipsoidal shape of our earth.

The length of daylight changes as the earth changes its position relative to the sun. The biggest differences in daylight manifest in twenty-four hour days or twenty-tour hour nights. These occur during the summer and winter solstices in locations within the Arctic and Antarctic. (Retrieved on 09/28/06 from source, http://members.aol.com/pakulka/emstyg2.htm)

The seasons on earth are controlled by changes in the intensity and duration of solar radiation or insolation. These factors are in turn governed by the annual change in the position of the Earth’s axis relative to the sun. Yearly changes cause the location of the sun to wander 47° across our skies. Positioning of the sun has a direct effect on the intensity of solar radiation. The angle of incidence is the angle at which the sun’s rays strike the surface of the earth; this determines the intensity of solar radiation.

If the sun is positioned directly overhead, the incoming insolation strikes the surface of the Earth at right angles and is most intense. If the sun is 45° above the horizon, the incoming insolation strikes the Earth’s surface at an angle; therefore it is not a direct hit to one small area. The rays are then spread out over a larger surface area reducing the intensity of the radiation. (Retrieved on 09/28/06 from source, http://www.physicalgeography.net/fundamentals/6i.html)

Astronomer Milutin Milankovitch developed the Milankovitch Cycles, which are the mathematical formulas upon which orbital variations are based. He hypothesized that these cyclic variations are responsible for major changes to the earth’s climate over the last 450,000 years; even ice ages. (Retrieved 09/28/06, from source, Hays, J.D. John Imbrie, and N.J. Shackleton. “Variations in the Earth’s Orbit: Pacemaker of the Ice Ages.” Science. Volume 194, Number 4270 (1976). 1121-1132.) The above is an example of the earth-sun relationship and its effect on the earth’s geography.