Many people are aware of the "ring of fire" as it pertains to geology - a zone surrounding the Pacific Ocean basin characterized by high levels of seismic and volcanic activity. The "ring of fire" also exists in meteorology, and is often observed in the summer, when upper level ridges of high pressure settle across the southern or southeastern portions of the nation. Underneath the high pressure, downward motion occurs and conditions are stable. However, around the periphery of the ridge, upper level disturbances and moisture riding around the ridge can allow thunderstorms to form. The image below is an example taken from Sunday evening, June 26th, near 8 PM EDT. If you were to look at a loop of this image, you would see the thunderstorm complexes rotating in a clockwise fashion around the periphery of the ridge over the southern plains.
Note that in just one hour, 21,002 lightning strikes were observed across the country! We just finished the annual Lightning Safety Awareness Week, but it is always good to remind ourselves of the danger lightning poses, not only from strong or severe storms, but even from a weak and otherwise non-severe summertime thunderstorm.