The occurrence of dome seeing has been linked by researchers to a variety and cumulation of several sources of heat transfer and air flow phenomena inside the telescope enclosure. Fig. below shows schematically the main causes that are generally considered to be source of dome seeing.
Figure: Causes commonly held to be source of dome seeing:
Most observatories have taken actions in the course of time to reduce most of these effects by insulating wall and floor surfaces and by extracting the heat generated by electric equipment items by means of active cooling circuits. However the relative importance of the different causes and consequently the definition of the technical actions best suited to provide a seeing-free environment has remained controversial.
In fact, the key for understanding the dome seeing phenomenon lies in a correct appreciation of the different free convection flow patterns which may be found in the air volume crossed by the optical beam. A main characteristic of free convection flow lies in the fact that temperature gradients and fluctuations are greatest close to the heat exchange surface while the far region experiences the largest velocities (see for instance [Townsend], pp. 381-392). Thus one shall expect that the seeing disturbance decreases rapidly with the distance from the heat exchange surface.