Isotachs - Hurricane Ike

https://www.e-education.psu.edu/meteo241/scatterometry

Isotach lines denote areas of constant wind speed.  Wind speed, which can vary based off of surface pressure and vise versa, can also be used to track storm systems.  But, knowing wind speeds at a high spatial resolution through ground stations is extremely difficult and expensive.  It is because of this problem that wind speeds began to be detected through remote sensing satellites such as QuickSCAT and ASCAT.  Through these satellites we can get a higher spatial resolution but sacrifice accuracy when calculating wind speeds.

In the image above, Hurricane Ike's winds are depicted through using this remotely sensed data.  Isotach lines have been drawn in as well.  Because winds are a function of pressure and the structure of a hurricane creates large pressure gradients in concentric circles from the eye, we can see that the isotachs also exist in concentric circles as well.  As we move closer to the center of the eye, we experience greater wind speeds.