S wave -- a shadow zone appears when the velocity suddenly decreases 103-180 degrees from the epicenter. Describe the differences between P and S waves. P waves expand and contract, can move through liquid solid and gas. S wave moves up and down or side to side moves through only solids.
Optimal conditions to see the northern lights in Iceland is when skies are clear and dark (away from the city lights, in cold temperature and ideally from mid-September to mid-April.
Question: Can you see the northern lights in summer in Iceland? First of all, if you are new to Iceland and it hasnât been on your radar for very long thereâs a very important thing you need to know about this marvelous island in the middle of the Atlantic ocean.