Why is the stratosphere isothermal

The freed electrons travel within the ionosphere as electric currents. Because of the free ions, the ionosphere has many interesting characteristics. At night, radio waves bounce off the ionosphere and back to Earth. This is why you can often pick up an AM radio station far from its source at night. The Van Allen radiation belts are two doughnut-shaped zones of highly charged particles that are located beyond the atmosphere in the magnetosphere.

The particles originate in solar flares and fly to Earth on the solar wind. These lines extend from above the equator to the North Pole and also to the South Pole then return to the equator. When massive solar storms cause the Van Allen belts to become overloaded with particles, the result is the most spectacular feature of the ionosphere—the nighttime aurora.

The particles spiral along magnetic field lines toward the poles. The charged particles energize oxygen and nitrogen gas molecules, causing them to light up. Each gas emits a particular color of light. There is no real outer limit to the exosphere , the outermost layer of the atmosphere; the gas molecules finally become so scarce that at some point there are no more.

Beyond the atmosphere is the solar wind. The solar wind is made of high-speed particles, mostly protons and electrons, traveling rapidly outward from the Sun. Skip to main content. The Atmosphere. Search for:. When gas molecules are cool, they are sluggish and do not take up as much space. With the same number of molecules in less space, both air density and air pressure are higher.

When gas molecules are warm, they move vigorously and take up more space. Air density and air pressure are lower. This is the recent Gold-Humphreys or Humphreys-Gold explanation as to why the stratosphere is vertically isothermal; viz. This discovery is probably destined to remain conspicuous in the annals of meteorology for two reasons; first, because of its intrinsic importance, and, secondly, because of the following remarkable chronological parallelism in its independent development by two investigators:—.

You can also search for this author in PubMed Google Scholar. Reprints and Permissions. The Isothermal Layer of the Atmosphere. Nature 93, 84 Download citation. Why does the temperature increase with height in the stratosphere? The importance of the ozone layer lies in the facts that 1 ozone helps the earth to maintain its heat balance, and 2 ozone reduces the amount of harmful UV radiation that reaches the earth's surface.

Mesosphere 0 deg to deg C. The mesosphere resides from about 50 km to km above the earth's surface. Because There is not enough oxygen to breathe here, although the percentage of oxygen in the atmosphere is about the same. There is not a layer of ozone to cause heating, so temperatures are colder as height increases. Thermosphere deg to deg C. The thermosphere lies above about 90 km. Unlike in the troposphere and stratosphere, temperatures in the thermosphere can change by hundreds of degrees depending on the amount of solar activity.

This region marks where the percentage of atmospheric constituents change. All Rights Reserved. The reason is that the troposphere's gases absorb very little of the incoming solar radiation. Instead, the ground absorbs this radiation and then heats the tropospheric air by conduction and convection. Since this heating is most effective near the ground, the temperature in the troposphere gradually decreases with increasing altitude until the tropopause is reached.

This is the beginning of the stratosphere. In the stratosphere, the temperature remains isothermal until about 20 km. Then a strange thing happens--the temperature actually begins to increase with altitude. From a temperature of about The reason for this temperature fluctuation is that ozone absorbs the uvb radiation in the lower atmosphere.

Higher in the atmosphere, however, normal diatomic oxygen absorbs the uvc radiation. Once it is absorbed, it is reradiated at different wavelengths, thereby warming the stratosphere. At the top of the stratosphere about 50 km, the stratopause , the temperature begins to decrease again as the altitude increases.

Above the stratopause, in the mesosphere, thermosphere, and exosphere harmful gamma rays and X-rays are absorbed.