The balanced atmosphere

Budgets and Cycles

A budget is a balance sheet of all the sources and sinks for a particular species or group of species in a single reservoir or in two or more connected reservoirs.

In an earth system budget all of the input or output processes important for the system might not have been identified. Even if they are they might be uncertain.

Lets examine the diagram on the right. It represents a tub receiving water from several faucets and having a number of drains of different sizes. When the water is supplied at constant (but different) rates by all the faucets and is removed at an equal total rate by drains with different flows, the water level remains constant.

When the tank is very large and has some wave motion that makes it difficult to tell if the water level is changing it might be difficult to decide if the system is in balance or not. In that case, it might be easier to measure the rate of supply from each of the faucets and the rate of removal in each of the drains over a period of time.