The lengths of day and night change seasonally in Iceland, thereby creating certain unique weather patterns. In midwinter, there is a period without sunlight, when darkness remains throughout the day and night - this phenomenon is called a "Polar Night". Again, in midsummer, the opposite of this takes place- the sun shines continually and there is no darkness during nights, giving rise to what is known as the "Midnight Sun".
During both these times, tourists are attracted to Iceland. In midsummer due to the cool and pleasant climate, and in midwinter, to see the "Northern Lights" or the Aurora Borealis during the long Polar Nights. The unique and pleasant weather is one of the features that makes Iceland special.