Air at either pole moves in large-scale and persistent cyclones called the polar vortices. These vortices extend from the mid and upper-level troposphere in to the stratosphere. They enclose the polar highs, the regions of high atmospheric pressure around either pole, and lie in the wake of the polar fronts.Know More
The vortices alternate in strength depending on the season in each hemisphere. They are generally larger and stronger in winter than they are in summer. Their size depends on the difference in temperature between the equator and the poles.
The temperature at the equator remains almost constant all year round, while the temperature at either pole depends on the Earth’s rotational tilt relative to the sun, which gives rise to seasons. In winter, the respective pole tilts away from the sun, leading to lower temperature. This causes the temperature difference between the pole and the equator to widen, leading to stronger and larger polar vortices.
The size of the polar vortices rarely exceeds 1,000 kilometers in diameter. Their rotational direction is flipped at either pole, due to the Coriolis force. The northern hemisphere polar vortex rotates counterclockwise, while the southern hemisphere vortex rotates clockwise. The foci of the northern polar vortex are often at Baffin Island Canada and Siberia.Learn more about Atmosphere
Air is a mixture, not a compound. Scientists define a mixture as a heterogeneous blend of molecules and atoms in variable proportions, while a compound is a substance formed by the chemical combination of two or more elements in fixed proportions.Full Answer >
Air seems thinner at high altitudes because air pressure is lower, which allows individual air molecules to occupy a larger volume than air molecules do at low altitudes. This decreasing pressure with increasing altitude occurs because there are increasingly fewer air molecules exerting pressure on the next-lowest altitude.Full Answer >
The thickest layer of the atmosphere is the troposphere, which averages 11 miles high at the equator and is thinner at the poles. All the weather occurs in this layer, and the troposphere contains nearly 80 percent of the air in the Earth's atmosphere. Above the troposphere, in ascending order, is the stratosphere, mesosphere, thermosphere and exosphere.Full Answer >
The troposphere, the lowest layer of Earth's atmosphere, varies in thickness from 12 miles (65,000 feet) at the equator to only four miles (23,000 feet) near the poles. This layer's thickness changes by as much as seven miles when air density gradually alters due to warming at the surface during different seasons. These shifts in density are most pronounced around mid-latitudes between the tropics and the poles.Full Answer >