# Science: An Elementary Teacher’s Guide/Earth's Atmosphere

Atmosphere is the envelope of gases surrounding the earth or another planet. Atmosphere does so much for the environment, such as controls the amount of heat lost and gained on the earth. It has the ability to know how much heat or cold be need so people on Earth won't fry up from all the sun and keeps up from freezing as well. The atmosphere protect all of us from extreme temperatures. Unfortunately, this shield of an atmosphere is under alot or risk due to all the pollution being brought up to the air. The moon is the complete opposite because their is no atmosphere, temperatures can reach very low and high degrees. Days on the moon are long than days on the earth, by about 28 times. The atmosphere is thickest and heaviest near the surface of the earth. The atmosphere is said to be layered.

## Air

We live in an ocean of air composed of a mixture of gases we call the atmosphere
Our atmosphere is unique among our solar system
Serves as an insulating blanket (moderates temperature swings) atmosphere is the envelope of air all round the extends 1600 km above the earth surfaces it contains all the gases which are essential for life and also provide us to breathe

## Earth's Atmosphere

* 78% Nitrogen
* 21% Oxygen
Animals require oxygen for fuel and Oxygen is highly reactive with other substances
* 1% Carbon Dioxide, Hydrogen, Helium, etc.
Plants use Carbon Dioxide and give off Oxygen as a waste product=Symbiotic relationship
The Atmosphere is NOT an inexhaustible sewer! Earth's atmosphere is about 300 miles (480 kilometers) thick, but most of it is within 10 miles (16 km) the surface. Air pressure decreases with altitude. At sea level, air pressure is about 14.7 pounds per square inch (1 kilogram per square centimeter). The atmosphere is an important part of what makes Earth livable. It blocks some of the Sun's dangerous rays from reaching Earth. It traps heat, making Earth a comfortable temperature. And the oxygen within our atmosphere is essential for life. Over the past century, greenhouse gases and other air pollutants released into the atmosphere have been causing big changes like global warming, ozone holes, and acid rain.

## Layers of atmosphere:
### Troposphere- 0-10 miles

Where most weather conditions occur and the atmosphere is most dense. A lot of water vapor is in this part of the atmosphere, producing clouds and storm
* The troposphere is the lowest layer of Earth's atmosphere.
* The troposphere starts at Earth's surface and goes up to a height of 7-20 km which is about 4-12 miles, or 23,000- 65,000 ft above sea level.
* Most of the mass (about 75-80%) of the atmosphere is in the troposphere. Almost all weather occurs within this layer.
* This layer is where most commercial and passenger airplanes fly.

### Stratosphere- 10-20 miles

Air in this layer is thin, cloudless and no weather happens here.
This layer of the atmosphere contains the ozone layer and the highest proportion of ozone gas that helps to absorb most of the ultraviolet rays that our planet receives from the sun. Unfortunately, in the early 1980s a significant drop in the stratospheric ozone became evident during the spring in the South Polar region to the point where a "hole" began to appear above the Antarctic. In the last 25 years, the ozone layer has thinned by 4%. This is linked to the production of chemicals by humans.
Some impacts of the ozone hole on human health and ecosystems include:
* Development of skin cancer.
* Severe exposure to UV rays is dangerous to the eyes increasing incidence of cataracts in particular.
* UV rays can affect our immune systems, lowering resistance to diseases and reducing the effectiveness of vaccines.
* Increase of UVs have negative effect on plant growth, lower yields from some plants and cereal crops and falling plankton populations.
* About 20% of the atmospheres mass is contained in the stratosphere.
* The stratosphere is stratified in temperature with warmer layer higher and cooler layers closer to the Earth.
* The increase of temperature with altitude, is a result of the absorption of the sun's ultraviolet radiation by ozone.

### Mesosphere- 20-50 miles

This is the third layer up from the ground. This contains at its outer edge the mesopause, the coldest portion of the atmosphere on earth. The temperatures of this layer can reach lows around -101 Celsius depending on the time of year.
* Above the maximum altitude for all aircraft, and most balloons.
* Strong east-west winds (atmospheric tides).
* The upper part has earth's coldest temperatures: -226 F; -143 C
* About thirty miles up.

### Ionsphere- 50-500 miles

Invisible layers of ions and electrons extending from a portion of the mesosphere as well as the thermosphere and the exosphere
* Upper atmosphere where atoms are ionized by solar radiation (electrons are added or removed, resulting in charged particles). Aurora borealis
* Shortwave radio waves bounce off the ionosphere, allowing long-distance communications.
* About 50-600 miles, then it's outer space!

### Exosphere- 500-space

Where the atmosphere thins out and merges with space
In the Northern Hemisphere, the winds are deflected (turned away) to their right by the Earth's rotating motion. In the Southern Hemisphere, the winds are deflected to their left. This is due to the Coriolis effect.
* Some molecules are still bound by gravity to earth, but there are so few of them that they rarely collide with each other.
* No clear boundary between the exosphere and outer space.

# Troposphere

Is the lowest part of the atmosphere it contains most of our weather clouds, rain, and snow. In this part of the atmosphere the temperature gets colder as the distance above the earth increases about 6.5°C per kilometer. The troposphere contains about 75 percent of all of the air in the atmosphere and almost all of the water vapor which forms clouds and rain.

# Stratosphere

This extends upwards from the troposphere to about 50 km. It contains much of the ozone in the atmosphere and increase in temperature with height occurs because of absorption of ultraviolet radiation from the sun by this ozone.

## Air Pollution

occurs when harmful substances including particulates and biological molecules are introduced into Earth's atmosphere. It may cause diseases, allergies or death in humans; it may also cause harm to other living organisms such as animals and food crops, and may damage the natural or built environment. What do smog, acid rain, carbon monoxide, fossil fuel exhausts, and tropospheric ozone have in common? They are all examples of air pollution. Air pollution is not new. As far back as the 13 th century, people started complaining about coal dust and soot in the air over London, England. Since the beginning of the industrial revolution in the late 1700s, we have been changing the Earth's atmosphere and its chemistry. As industry spread across the globe, so did air pollution. Air pollution has many effects. In addition to being ugly, it can cause illness and even death. It damages buildings, crops, and wildlife. The worst air pollution happened in London when dense smog (a mixture of smoke and fog) formed in December of 1952 and lasted until March of 1953. 4,000 people died in one week. 8,000 more died within six months.
Air pollution is made up of solid particles and chemicals. Natural processes impacting the atmosphere include volcanoes, biological decay, and dust storms. Plants, trees, and grass release volatile organic compounds (VOCs), such as methane, into the air. We are more concerned with human-made pollution since we have the ability to control it. The pollutants include carbon monoxide, sulfur dioxide, VOCs, and nitrogen oxides. The largest source of human-made pollution is the burning of fossil fuels, including coal, oil, and gas, in our homes, factories, and cars.
Air pollution is either primary or secondary. Primary pollution is put directly to the air, such as smoke and car exhausts. Secondary pollution forms in the air when chemical reactions changes primary pollutants. The formation of tropospheric ozone is an example of secondary air pollution.
The atmosphere is a complex, dynamic and fragile system. Concern is growing about the global effects of air pollution, especially climate change. Stratospheric ozone depletion due to air pollution has long been recognized as a threat to human health.
* ↑ "ISS022-E-062672 caption". NASA. Retrieved 21 September 2012.