Uploaded on 2016-08-30 by Marta

An example of stocks could be the water in lakes or reservoirs. This does not move, it is not exported or imported from other countries directly. However, these amounts of water could change over time due to global warming or if they are artificially taken out. Airplanes are considered flow, because they allow the movement between countries and the export and import of goods. The number of airplane flights might either increase due to a higher demand for international products or on the other hand, it could drastically decrease if a faster and more reliable method of transport is found.