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Tropical year. A tropical year or solar year (or tropical period) is the time that the Sun takes to return to the same position in the sky – as viewed from the Earth or another celestial body of the Solar System – thus completing a full cycle of astronomical seasons. For example, it is the time from vernal equinox to the next vernal equinox ...
A season is a division of the year [ 1 ] based on changes in weather, ecology, and the number of daylight hours in a given region. On Earth, seasons are the result of the axial parallelism of Earth's tilted orbit around the Sun. [ 2 ][ 3 ][ 4 ] In temperate and polar regions, the seasons are marked by changes in the intensity of sunlight that ...
22.1–24.5° range of Earth's obliquity. The angle of the Earth's axial tilt with respect to the orbital plane (the obliquity of the ecliptic) varies between 22.1° and 24.5°, over a cycle of about 41,000 years. The current tilt is 23.44°, roughly halfway between its extreme values.
Seasons on planets. The start and end dates of a season on any planet of the Solar System depends on same factors valid on Earth, but which have different values on different planets: All these factors affect how much energy from Sun falls on all the points at a same given latitude (i.e. a parallel) on the planet during daytime; if such amount ...
Geological cycles. Age of the Earth – Aluminum cycle – Arsenic cycle – Boron cycle – Bromine cycle – Cadmium cycle – Calcium cycle – Carbonate–silicate cycle – Chlorine cycle – Chromium cycle – Climate change – Copper cycle – Cycle of erosion – Dynamic topography – Dynamic topography – Earthquake cycle ...
Solar activity and climate. Solar irradiance (yellow) plotted with temperature (red) since 1880. Patterns of solar irradiance and solar variation have been a main driver of climate change over the millions to billions of years of the geologic time scale. Evidence that this is the case comes from analysis on many timescales and from many sources ...
Photoperiod is the change of day length around the seasons. The rotation of the earth around its axis produces 24 hour changes in light (day) and dark (night) cycles on earth. The length of the light and dark in each phase varies across the seasons due to the tilt of the earth around its axis. The photoperiod defines the length of the light ...
List of solar cycles. Solar cycles are nearly periodic 11-year changes in the Sun 's activity that are based on the number of sunspots present on the Sun's surface. The first solar cycle conventionally is said to have started in 1755. The source data are the revised International Sunspot Numbers (ISN v2.0), as available at SILSO. [1]