IBL - The Atmosphere Lesson

 

The Atmosphere

An atmosphere is a layer of gases surrounding a planet that is held in place by gravity. The atmosphere has been changing since the Earth was created 4.6 billion years ago. Once living things were able to carry out photosynthesis, the Earth's atmosphere has constantly changed indicating the strong relationship between the atmosphere and life on earth.

The Earth started with no atmosphere and no gases, to forming water droplets, to carbon dioxide, the formation of oxygen, and then the ozone - there have been many different compositions. The current composition of the Earth's atmosphere is the product of billions of years of biochemical modification by living organisms.

The modern atmosphere includes primarily nitrogen (78%), oxygen (21%), argon (.9%), carbon dioxide (.04%) and small amounts of other gases. Air also contains a variable amount of water vapor, 1% at sea level and .4% over the entire atmosphere. In addition, the atmosphere contains dust, smoke, pollen, and acid droplets. The composition of the atmosphere is constantly changing depending on the season, weather, time of day, position of the globe, etc. The atmosphere as we know it today is necessary for life on Earth by protecting and transporting materials.

Protection

For billions of years, our atmosphere has protected us against meteorites, as shade against ultraviolet radiation, and as a blanket against the cold.

Flip through the images below to learn more about the protective layers of the atmosphere.

Movement of Substances

The air in the atmosphere is never still or stagnant.  As we have already studied, warmed by the sun's heat, air moves in currents around the globe. With this movement, the air picks up particles, seeds, microscopic organisms, smoke, etc. Atmosphere hitchhikers can move particles 1000s of miles, altering known life, air quality, and weather - thus transforming life.

As you learned already, the atmosphere is a major reservoir for nutrient cycling including carbon, oxygen, phosphorus, nitrogen, and water.  

There are instances when the movement of substances can have disastrous effects on life.

The Gobi Desert is rich in iron. Every spring it travels across China, Korea, and Japan to the North Pacific Ocean. Here it creates a phytoplankton bloom causing fish to thrive.  While Beijing chokes on dust, fishermen benefit from the rich fishing grounds.

The Sahara Desert will blow red dust toward the Caribbean seas. The coral sucks in the dust as it filters water for food. The dust has viruses and bacteria in it which can cause infections to the corals that would not have been there. Damaged coral loses its color as shown in the image.

Review the vocabulary for this module:

 

IMAGES CREATED BY GAVS OR OPENSOURCE