There are a lot of things about our planet that are like that. Pages 28-31 of Dr. Art's Guide to Planet Earth provides an example of dynamic balance. The amount of water in each of the reservoirs of the water cycle stays fairly constant even though water is constantly flowing into and out of that reservoir. We call this kind of situation dynamic balance. Dynamic means things are happening.
Balance means there is no total change.
Water in the ocean is dynamic - it keeps leaving through evaporation and returning through precipitation and runoff. Yet, the total amount of water in the ocean is not changing, so we say it is in balance. Determine the consequences of atmospheric alteration to biological systems. Predict and illustrate future physical and biological changes on Earth based on current atmospheric trends. Analyze the transfer of energy within Earth systems.