This passage is an example of cause and effect, one of the existing text structures.
Text structures are related to the way in which information is organized in a specific text. Cause and effect is one of the patterns of organization and it is used to explain why something happens and what are the results or consequences of that event. In the case of this passage, the phenomenon that is being discussed is the tornado. Moreover, the excerpt states its causes (unstable air interacting with the wind shear) and effects, which are described as 'devastating'.
