Earth's Oceans and Deserts Help (page 2)

By — McGraw-Hill Professional
Updated on Apr 25, 2014

Layers Of The Atmosphere

The Earth’s atmosphere is 78 percent nitrogen at the surface and 21 percent oxygen. The remaining 1 percent consists of argon, carbon dioxide, ozone, and water vapor. The temperature of the atmosphere varies considerably; it can rise to about 55°C (130°F), or plunge to around –80°C (–112°F).

The lowest layer of the atmosphere, rising from the surface to approximately 16 km (10 mi) of altitude, is the troposphere . This is where all weather occurs; most of the clouds are found here. In the upper parts of the troposphere, high-speed rivers of air travel around the planet in a generally west-to-east direction. There can be two or three of these rivers in the northern hemisphere and two or three in the southern hemisphere. The strongest of these rivers, called jet streams , carry high- and low-pressure systems from west to east at temperate latitudes, primarily between 30°N and 60°N, and between 30°S and 60°S.

Above the troposphere lies the stratosphere , extending up to approximately 50 km (30 mi) of altitude. Near the upper reaches of this level, ultraviolet radiation from the Sun causes oxygen atoms to group together into triplets (O 3 ) rather than in pairs (O 2 ), as is the case nearer the surface. An oxygen triplet is a molecule known as ozone . This gas has the unique property of being opaque to ultraviolet rays. Thus oxygen atoms form a self-regulating mechanism that keeps the Earth’s surface from receiving too much ultraviolet from the Sun. Certain gases are produced by industrial processes carried on by the two-legged humans; these gases rise into the stratosphere and cause the ozone molecules to break apart into their individual atoms. This makes the upper stratosphere more transparent to ultraviolet than it would be if nature had its way. Some humans have demonstrated that if this process continues, it could have an adverse effect on all life on the planet. Other humans do not believe this and continue to produce these potentially dangerous industrial by-products.

Above the stratosphere lies the mesosphere , extending from 50 km (30 mi) to an altitude of 80 km (50 mi). In this layer, ultraviolet radiation from the Sun causes electrons to be stripped away from atoms of atmospheric gas. The result is that the mesosphere contains a large proportion of ions. This occurs in a layer that communications engineers call the D layer of the ionosphere .

Above the mesosphere lies the highest layer of the Earth’s atmosphere, known as the thermosphere . It extends from 80 km (50 mi) up to more than 600 km (370 mi) of altitude. This layer gets its name from the fact that the temperature is extremely high, even hotter than at the surface of Venus or Mercury. However, these high temperatures do not have the devastating effects they would have if they existed at the surface because the atmosphere at this level is so rarefied. Ionization takes place at three levels within the thermosphere, called the ionospheric E layer, F1 layer , and F2 layer . Sometimes, particularly at night, the F1 and F2 layers merge together near the altitude of the F2 layer; the resulting layer is called the F layer . Figure 8-4 is a diagram of the Earth’s atmosphere showing the various layers and the ionized regions.

An Extraterrestrial Visitor’s Analysis of
Earth Anatomy Of Earth Layers Of The Atmosphere

Figure 8-4. The Earth’s atmosphere, showing the ionized layers.

Excerpt From A First Officer’s Journal

I have just received a stern warning from the authorities back home on Epsilon Eridani 2. Their mandates are as follows:

  • Our Earth landing assignments have been reduced from 10 to 3.
  • We are not to land within 50 km (30 mi) of any place known to be populated, even sparsely, with the two-legged life forms that call themselves Homo sapiens .
  • We are to keep our radar and optical cloaking devices activated at all times.
  • If we accidentally happen to encounter any Homo sapiens , we are to explain to them that we are part of a “Hollywood movie set” and then ask them to leave.

This seems to defeat the most important part of our mission: to find out exactly what makes Homo sapiens behave as they do. However, I can’t fight the bureaucracy of Epsilon Eridani 2! I will have to be content with looking at these creatures, whom I have decided to call bipedal ants , through telescopes while in orbit and analyzing their migration patterns with radar and computer programs.

North Atlantic Ocean

We descend into the middle of the Azores-Bermuda high-pressure system in the North Atlantic Ocean, hoping to find calm conditions. It is the part of the Earth year that the bipedal ants call April , when hurricanes are unknown in this part of the planet. Nevertheless, when we reach the ocean, we find that there are huge waves on the surface. The waves come from the north, and we recall that storms can track across the North Atlantic at any time of the year.

In the northern-hemispheric spring, storms follow the jet stream, coming off the North American continent near the mouth of the St. Lawrence Seaway and taking paths at high latitudes toward Europe. Our meteorology expert on the main ship confirms that one of these storms is passing near Iceland, and it is responsible for generating the waves. We are surprised that waves can travel so far and still be so large, but the main-ship radar telescope indicates that their effects reach all the way south to Antarctica.

The atmosphere is perfectly calm; there is no wind as we land and observe a temperature of 23°C (73°F) at high noon. We float like a cork on the swells, which measure 11 m (36 ft) from crest to trough. The surface of the water is smooth except for these sine-wave-shaped swells, a most remarkable phenomenon.

By sunset, the temperature of the atmosphere has hardly changed; it is 22°C (72°F). At midnight, the atmospheric temperature has gone down to 20°C (68°F), and just before sunrise on the day after our landing, it is at its minimum of 19°C (66°F). This small temperature variation between day and night confirms our theory that the oceans keep the lower atmospheric temperature relatively stable. The water temperature is measured at 20°C (68°F).

We remain on the surface of the ocean, examining the abundant life in the water, for exactly one solar day. We see no signs of the bipedal ants, either on the surface of the ocean or in the atmosphere above it, even though we have been told that aircraft will fly overhead and one of them will descend to investigate us. We are relieved when we lift off at noon, exactly 24 Earth hours after we landed. Because of the violent and continuous motion induced by the waves, I have lost 2.5 kilograms (kg) of body weight. This is 5.5 pounds (lb) in the Earth’s gravitation. It has taken place because I have been unable to eat or drink anything for the past 24 Earth hours without having it come back up. Many bipedal ants suffer this same malady when they are first introduced to oceanic travel; they call it sea-sickness .

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