Hopefully, now that you know what to look for, these 20 amino acids are not too complicated molecularly. In fact, the only thing that is different in these 20 amino acids is the group of atoms attached to the central carbon at this central carbon's fourth covalent bond (by convention, shown above the central carbon). For example, the simpliest amino acid only has a single hydrogen atom attached as this side group.
Water vapor and particles of dust can also be found in the earth's air. Clouds float only in the troposphere, or the lowest part of the atmosphere. It is also here that all of the earth's wind, storms and other features of weather take place. The troposphere extends upward to a height of about 10 miles. Air gets thinner the farther it gets from earth. The stratosphere extends from the troposphere to about 30 miles above the earth. It is in this air that many jet airplanes fly.
The troposphere is wider at the equator (10mi) than at the poles (5mi). The troposphere contains 75 percent of atmosphere's mass- on an average day the weight of the molecules in the air is14.7 lb..(sq. in.)- and most of the atmosphere's water vapor. Water vapor concentration varies from trace amounts in Polar Regions to nearly 4 percent in the tropics.