Some recent studies even suggest that over tens of millions of years, the swing may be as much as 0° to 60°. By contrast, the obliquity cycle for Mars is much more extreme: from 15° to 35° over a 124,000-year cycle. ![]() These and other similar cyclical changes are thought to be responsible for ice ages (see Milankovitch cycles). ![]() Thus, for example Earth's eccentricity of about 1% regularly fluctuates and can increase up to 6%, and at some point in the distant future the Earth will also have to deal with the calendrical implications of seasons of widely differing length and the major climate disruptions that go along with it.Īside from the eccentricity, the Earth's axial tilt can also vary from 21.5° to 24.5°, and the length of this "obliquity cycle" is 41,000 years. The axial tilt and eccentricity of Earth (or Mars) are by no means fixed, but rather vary due to gravitational perturbations from other planets in the Solar System on a timescale of tens of thousands or hundreds of thousands of years. This is similar to the effect in Earth's deserts, only much more pronounced. On a daily basis, temperatures peak at local solar noon and reach a minimum at local midnight. The temperature variations between spring and summer are much less than the very sharp variations that occur within a single Martian sol (solar day). However, in the southern hemisphere the opposite is true. The only difference between spring temperatures and summer temperatures is due to the relatively high eccentricity of Mars's orbit: in northern spring Mars is farther from the Sun than during northern summer, and therefore by coincidence spring is slightly cooler than summer and autumn is slightly warmer than winter. Thus, for temperatures on Mars, "spring" is approximately the mirror image of "summer" and "autumn" is approximately the mirror image of "winter" (if you consider the solstices and equinoxes to be the beginnings of their respective seasons), and if Mars had a circular orbit the maximum and minimum temperatures would occur a couple of days after the summer and winter solstices rather than about one month after as on Earth. The seasonal lag on Mars is no more than a couple of days, due to its lack of large bodies of water and similar factors that would provide a buffering effect. Mars sky at sunset, as imaged by the Curiosity rover (February 2013 Sun simulated by artist). Therefore, extremes of temperature are considerably wider in the southern hemisphere than in the north. Similarly, summers in the north are long and cool, while summers in the south are short and hot. Winters in the north are warm and short (because Mars is moving fast near its perihelion), while winters in the south are long and cold (Mars is moving slowly near aphelion). In practical terms, this means that summers and winters have different lengths and intensities in the northern and southern hemispheres. Season (considering the beginning to be the respective solstice or equinox) ![]() Therefore, the seasons are of unequal length, much more so than on Earth: However, the orbit of Mars has significantly greater eccentricity than that of Earth. As on Earth, the southern and northern hemispheres have summer and winter at opposing times. Mars has an axial tilt of 25.19°, quite close to the value of 23.44° for Earth, and thus Mars has seasons of spring, summer, autumn, winter as Earth does. See also: Climate of Mars and Timekeeping on Mars
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |