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.
Planning to see the Northern Lights in Iceland. There is no guarantee to see the Northern Lights, even if you are in the best areas. However, a bit of planning will radically increase your chances.In Iceland, good periods are between from late August to mid April.1. Darkness is required.nd the ideal place to see Northern Lights is Iceland: Astronomers are predicting that the Northern Lights will be some of the brightest in decades over the next few years due to a peak in the solar cycle, so now is the time to visit. Experience a wonder of nature in Iceland!