what happens to the temperature as altitude increases in the stratosphere

Lesson Objectives

• List the major layers of the atmosphere and their temperatures.
• Hash out why all weather condition takes identify in the troposphere.
• Discuss how the ozone layer protects the surface from harmful radiations.

Vocabulary

• aurora
• exosphere
• inversion
• ionosphere
• magnetosphere
• mesosphere
• ozone layer
• solar current of air
• stratosphere
• temperature gradient
• thermosphere
• troposphere

Introduction

The atmosphere is layered, corresponding with how the atmosphere's temperature changes with altitude. By understanding the way temperature changes with altitude, nosotros can learn a lot about how the atmosphere works. While conditions takes identify in the lower atmosphere, interesting things, such equally the beautiful aurora, happen higher in the atmosphere.

Air Temperature

Papers held up by ascent air currents above a radiator demonstrate the important principle that warm air rises.

Why does warm air rise (Effigy above)? Gas molecules are able to move freely and if they are uncontained, as they are in the temper, they can take up more than or less space.

• When gas molecules are cool, they are sluggish and practise not take up equally much space. With the same number of molecules in less infinite, both air density and air pressure are college.
• When gas molecules are warm, they move vigorously and take upwardly more space. Air density and air pressure are lower.

Warmer, lighter air is more than buoyant than the libation air to a higher place it, and then information technology rises. The cooler air then sinks downward, because it is denser than the air beneath it. This is convection, which was described in the Plate Tectonics affiliate.

The belongings that changes most strikingly with altitude is air temperature. Unlike the change in pressure level and density, which decrease with altitude, changes in air temperature are not regular. A change in temperature with altitude is called a temperature gradient.

The atmosphere is divided into layers based on how the temperature in that layer changes with altitude, the layer's temperature slope (Effigy below). The temperature gradient of each layer is different. In some layers, temperature increases with distance and in others information technology decreases. The temperature gradient in each layer is determined past the oestrus source of the layer (Effigy below).

The four master layers of the atmosphere have dissimilar temperature gradients, creating the thermal construction of the atmosphere.

The layers of the temper announced equally different colors in this image from the International Space Station.

Most of the important processes of the atmosphere accept identify in the lowest two layers: the troposphere and the stratosphere.

Troposphere

The temperature of the troposphere is highest near the surface of the Earth and decreases with altitude. On average, the temperature slope of the troposphere is 6.v°C per 1,000 m (3.half dozen°F per one,000 ft.) of altitude. What is the source of rut for the troposphere?

World'southward surface is a major source of heat for the troposphere, although nearly all of that heat comes from the Sun. Rock, soil, and water on World absorb the Sun's light and radiate information technology back into the atmosphere equally heat. The temperature is likewise college nearly the surface because of the greater density of gases. The college gravity causes the temperature to rising.

Observe that in the troposphere warmer air is beneath libation air. What do yous recall the consequence of this is? This status is unstable. The warm air virtually the surface rises and cool air higher in the troposphere sinks. So air in the troposphere does a lot of mixing. This mixing causes the temperature gradient to vary with time and place. The rising and sinking of air in the troposphere ways that all of the planet's weather takes place in the troposphere.

Sometimes there is a temperature inversion, air temperature in the troposphere increases with altitude and warm air sits over cold air. Inversions are very stable and may last for several days or even weeks. Inversions form:

• Over land at night or in winter when the ground is cold. The cold ground cools the air that sits in a higher place information technology, making this low layer of air denser than the air above it.
• Near the coast where cold seawater cools the air in a higher place information technology. When that denser air moves inland, it slides beneath the warmer air over the land.

Since temperature inversions are stable, they oftentimes trap pollutants and produce unhealthy air conditions in cities (Figure below).

Smoke makes a temperature inversion visible. The smoke is trapped in common cold dense air that lies beneath a cap of warmer air.

At the height of the troposphere is a thin layer in which the temperature does not alter with height. This means that the cooler, denser air of the troposphere is trapped beneath the warmer, less dense air of the stratosphere. Air from the troposphere and stratosphere rarely mix.

A science experiment that clearly shows how a temperature inversion traps air, along with whatever pollutants are in information technology, most the footing is seen in this video (5c): http://www.youtube.com/watch?v=LPvn9qhVFbM (2:50).

Stratosphere

Ash and gas from a large volcanic eruption may burst into the stratosphere, the layer above the troposphere. Once in the stratosphere, it remains suspended in that location for many years because there is and then petty mixing betwixt the ii layers. Pilots like to fly in the lower portions of the stratosphere because there is little air turbulence.

In the stratosphere, temperature increases with altitude. What is the heat source for the stratosphere? The directly heat source for the stratosphere is the Sunday. Air in the stratosphere is stable because warmer, less dense air sits over cooler, denser air. As a result, at that place is little mixing of air within the layer.

The ozone layer is found within the stratosphere betwixt 15 to xxx km (9 to 19 miles) altitude. The thickness of the ozone layer varies by the flavour and too by latitude.

The ozone layer is extremely important because ozone gas in the stratosphere absorbs most of the Sun's harmful ultraviolet (UV) radiation. Because of this, the ozone layer protects life on Earth. Loftier-energy UV calorie-free penetrates cells and damages DNA, leading to jail cell death (which we know as a bad sunburn). Organisms on Earth are not adapted to heavy UV exposure, which kills or damages them. Without the ozone layer to reverberate UVC and UVB radiation, virtually complex life on Earth would non survive long (Effigy below).

Even with the ozone layer, UVB radiation still manages to reach Earth's surface, especially where solar radiation is high.

Mesosphere

Temperatures in the mesosphere subtract with altitude. Considering there are few gas molecules in the mesosphere to absorb the Sun's radiation, the rut source is the stratosphere beneath. The mesosphere is extremely cold, especially at its top, nearly -xc°C (-130°F).

The air in the mesosphere has extremely depression density: 99.9% of the mass of the temper is below the mesosphere. As a issue, air pressure is very low (Effigy below). A person traveling through the mesosphere would experience severe burns from ultraviolet light since the ozone layer which provides UV protection is in the stratosphere beneath. At that place would be almost no oxygen for breathing. Stranger notwithstanding, an unprotected traveler's claret would boil at normal torso temperature because the force per unit area is so depression.

Meteors burn down in the mesosphere fifty-fifty though the gas is very thin; these burning meteors are shooting stars.

Thermosphere and Beyond

The International Space Station (ISS) orbits within the upper office of the thermosphere, at about 320 to 380 km higher up the Globe.

The density of molecules is and so depression in the thermosphere that one gas molecule can go about 1 km before it collides with another molecule. Since and so trivial energy is transferred, the air feels very cold (Figure above).

Within the thermosphere is the ionosphere. The ionosphere gets its name from the solar radiation that ionizes gas molecules to create a positively charged ion and 1 or more negatively charged electrons. 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 y'all can often selection up an AM radio station far from its source at night.

The Van Allen radiation belts are 2 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 Globe on the solar wind. Once trapped by World'due south magnetic field, they follow along the field's magnetic lines of force. These lines extend from above the equator to the N Pole and also to the Southward Pole then return to the equator.

When massive solar storms cause the Van Allen belts to get overloaded with particles, the result is the near spectacular feature of the ionosphere — the nighttime aurora (Effigy beneath). The particles spiral along magnetic field lines toward the poles. The charged particles energize oxygen and nitrogen gas molecules, causing them to lite up. Each gas emits a detail color of light.

(a) Spectacular lite displays are visible as the aurora borealis or northern lights in the Northern Hemisphere. (b) The aurora australis or southern lights encircles Antarctica.

There is no existent outer limit to the exosphere, the outermost layer of the atmosphere; the gas molecules finally go so deficient that at some point there are no more than. Beyond the temper is the solar air current. The solar wind is made of loftier-speed particles, mostly protons and electrons, traveling rapidly outward from the Lord's day.

This video is very thorough in its discussion of the layers of the atmosphere. Remember that the chemical composition of each layer is nearly the same except for the ozone layer that is constitute in the stratosphere (8a): http://www.youtube.com/watch?five=S-YAKZoy1A0 (6:44).

KQED: Illuminating the Northern Lights

What would Earth'southward magnetic field look like if information technology were painted in colors? It would expect like the aurora! This QUEST video looks at the aurora, which provides clues about the solar wind, Earth'south magnetic field and Earth's atmosphere. Learn more at: http://science.kqed.org/quest/video/illuminating-the-northern-lights/.

Lesson Summary

• Features of the atmosphere change with altitude: density decreases, air pressure decreases, temperature changes vary.
• Different temperature gradients create different layers within the temper.
• The everyman layer is the troposphere where most of the atmospheric gases and all of the planet's atmospheric condition are located. The troposphere is heated from the basis, so temperature decreases with altitude. Because warm air rises and cool air sinks, the troposphere is unstable.
• In the stratosphere, temperature increases with altitude. The stratosphere contains the ozone layer, which protects the planet from the Sun's harmful UV radiation.

Review Questions

1. Give a detailed explanation of why warm air rises.
2. Why doesn't air temperature alter uniformly with altitude? Requite examples.
3. Describe how the ground acts as the rut source for the troposphere. What is the source of energy and what happens to that free energy?
4. How stable is an inversion and why? How does an inversion form?
5. Phoenix, Arizona, is a city in the Southwestern desert. Summers are extremely hot. Winter days are ofttimes fairly warm just wintertime nights tin can exist quite dank. In December, inversions are quite common. How does an inversion course nether these conditions and what are the consequences of an inversion to this sprawling, car-dependent city?
6. Why tin can't air from the troposphere and the stratosphere mix freely?
7. What is the estrus source for the stratosphere? How is that heat absorbed?
8. Depict ozone cosmos and loss in the ozone layer. Does one occur more the other?
9. How and where are "shooting stars" created?
10. Why would an unprotected traveler'south blood eddy in the mesosphere?

Further Reading / Supplemental Links

• NASA, The Mystery of the Aurora: http://www.youtube.com/spotter?v=PaSFAbATPvk.

Points to Consider

• How does solar energy create the temper's layers?
• How does solar energy create the conditions?
• What would happen to life on Earth if in that location was less ozone in the ozone layer?

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Source: https://courses.lumenlearning.com/sanjac-earthscience/chapter/atmospheric-layers/

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