A square has four equal sides and it is a one-plane figure-like a sheet of paper. To determine how much surface area is enclosed within the square you multiply the length of one side by the length of the other equal side. If the sides were 1 centimeter (cm) in length the area of the square would be 1 cm x 1 cm = 1 square cm, or 1 cm²

.Now, if squares having an area of 1 cm² were stacked on top of each other until the stack was 1 cm tall, you would end up with a cube whose sides were each 1 cm in length. To determine the volume of the cube you simply multiply the length by the width and height. Because each side is 1 cm you end up with a volume of 1 cubic centimeter (cm³ ) (1 cm x 1 cm x 1 cm = 1 cm³). 

More simply stated, multiply the area of one side of the cube by the height of the cube. Once you understand how the volume of a cube is determined, you are now ready to review the G in the CGS system.

The conventional unit of weight in the metric system is the gram (gm). You could use table 1-1-1 and substitute the word gram for meter and the symbol (gm) for the symbol (M). You would then have a table for metric weight. The gram is the weight of 1 cm³ of pure water at 4C. At this point it may be useful to compare the weight of an object to its mass. The weight of the 1 cm³ of water is 1 gm. Weight and mass are proportional to each other. However, the weight of the 1 cm ³ of water changes as you move away from the gravitational center of Earth. In space the 1 cm³ of water is weightless, but it is still a mass. Mass is expressed as a function of inertia/acceleration, while weight is a function of gravitational force. When we express the move-ment of an object we use the terms mass and acceleration.

Time is measured in hours, minutes, and seconds in both systems. Hence, the second need not be explained in the CGS system. With a knowledge of how the CGS system can be used to express physical entities, you now have all the background to express such things as density and force.

With the previous explanation of grams and centimeters, you should be able to understand how physical factors can be measured and described. For example, density is the weight something has per unit of volume. The density of water is given as 1 gram per cubic centimeter or 1 gm/cm 3 . By comparison, the density of water in the English system is 62.4 pounds per cubic foot or 62.4 lb/ft³

.FORCE

Force is measured in dynes. A dyne is the force that moves a mass of 1 gram, 1 centimeter per square second. This is commonly written as gm cm per sec ², gm cm/sec/sec or gm/cm/sec². The force necessary for a gram to be accelerated at 980.665 cm/sec² at45 latitude is 980.665 dynes.

For more detailed conversion factors commonly used in meteorology and oceanography, refer to Smithsonian Meteorology Tables.

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