Equator

This is an imaginary line in the middle of the planet or other celestial body. This is half way between North pole and South pole at 0⁰altitude. This line divides the earth into two hemispheres – Northern Hemisphere and Southern Hemisphere. The earth is widest at its Equator covering an area of 40,075 kilometers/ 24,901 miles. The Earth’s diameter is wider at Equator which results into a phenomenon called Equatorial bulge. The diameter of a circle can be measured by a line that runs from end of the circle to the other end. Equator crosses over 16 countries on the planet, these countries are; Sao’ Tome’ and Principe, Gabon, Congo Brazzaville, Democratic Republic of Congo, Uganda, Kenya, Somalia, Indonesia, Ecuador, Colombia and Brazil. Equator also passes through territorial seas of 3 countries and these are Maldives, Kiribati and United States of America.

On and near the Equator, the noon-time appears almost directly overhead yea around. And on the other hand, Equator has its temperatures stable throughout the year. On the equinoxes that is March and September, the subsolar points cross the Equator at a very shallow angle, sunlight shines perpendicular to Earth’s axis of rotation and al latitudes have nearly 12 hours day and 12 hours night. The exact location of Equator is not fixed, due to Equatorial plane being perpendicular to the Earth’s rotation axis, this drifts it about 9 meters in the year. Geographical samples show that Equator changed positions about 48 and 12 million years as sediments deposited by the ocean thermal currents at the Equator shifted. The deposits by the oceanic thermal currents are determined by the axis of the earth which determines the solar coverage of the earth’s surface.

The changes in the Earth’s axis can be evidenced in the geographic layout of the volcanic Island chains which are created by hot spots under the Earth’s crust as the axis and crust move and this is constant with India’s tectonic plates colliding with Eurasian tectonic plates thus causing Himalaya uplift.

Length of the Equator

The International Association of Geodesy (AIG) and the International Astronomical Union (IAU) use the Equatorial radius of 6,378.1366 km (codified as IAU 2009 value). This Equatorial radius is in 2003 and 2010 International Earth’s Rotation Reference System (IERS) conventions. It is also Equatorial radius used for 2003 IERS ellipsoid.

The Earth is commonly modeled as a sphere flattened 0.336% along its axis and this makes Equator 0.16% longer than meridian (a great circle passing through the two poles). The sea level surface of the Earth is irregular so the actual length of Equator is not easy to determine.

Equatorial seasons and Climate

The seasons result from the tilt of the Earth’s axis away from the line perpendicular to the plane of its revolution around the sun. throughout the year, the Northern and Southern Hemispheres are alternately turned either toward or away from the sun depending on the Earth’s position in its orbit. The hemisphere turned to the sun receives more sun and it is in Summer while the other hemisphere that receives less sun is in winter.

At the equinoxes, Earth’s axis is perpendicular to the sun rather than tilted toward or away meaning that both day and night are about 12 hours across the whole Earth. Near the Equator this means that the variation in the strength of the solar radiation is relative to the time of the year than it at higher altitudes. Maximum solar radiation is received during equinoxes when the place at Equator is under the subsolar point at high noon and the intermediate seasons of the spring and autumn occur at high altitudes and the minimum occurs during both solstices when either the pole is tilted toward or away from the sun causing either summer or winter in both hemispheres. This also results in to corresponding movement of the Equator away from the subsolar point which is then situated over or near the relevant tropic circle. Even though temperatures are high year-round due to Earth’s axial tilt of 23.5⁰ not ^being enough to create a low minimum midday declination to weaken the sun rays during the solstice. High temperatures extend to about 25⁰ north or south of the Equator although the moderate seasonal temperature difference is defined by the opposing solstices near the poleward limit of this range.

Near the Equator, there is little temperature change throughout the year though there may be some differences in rainfall and humidity. Lowlands around the Equator have tropical rainforest climate also known as Equatorial climate though some cold ocean currents cause some regions to have Tropical monsoon climates with a dry season in the middle of the year, and the Somali current caused by the Asian monsoon due to continental heating via high Tibetan plateau causes Greater Somali to have an arid climate despite of the Equatorial location.

Average temperatures of the lowlands around the Equator are 31⁰C (88⁰F) during the afternoon and 23⁰C (73⁰ F) during the sunrise. Rainfall is very high away from the cold ocean currents upwelling zones from 2,500 mm to 3,500 mm per year. There are about 200 rainy days per year and 2,000 sunny hours per year. Despite high year-round sea level temperatures, some areas with higher altitudes such as Andes and Kilimanjaro have glaciers on their peaks. The highest point on Equator is on an elevation of 4,690 meters (15,387 ft), at 0⁰ 0’0N”77⁰ 59’31” W found on the southern slopes of Volcano Cayambe [summit 5,790 meter (18,9966ft)] in Ecuador.

This altitude is above the snow line and t is the only place on the Equator where snow lies on the ground. At the Equator, the snow line is around 1,000 meters (3,300 ft) lower than on the mountain Everest and as much as 2,000 meters (6,600 ft) lower than the highest snow line in the whole world near the Tropic of Capricorn on Llullaillaco.