The Northern Hemisphere is the half of a planet that is north of its equator—the word hemisphere literally means “half sphere”. It is also that half of the celestial sphere north of the celestial equator. Earth’s northern hemisphere contains most of the planet’s land, and roughly 90% of its human population. 

Due to the Earth’s axial tilt, winter lasts from the winter solstice (typically December 22) to the vernal equinox (typically March 20), while summer lasts from the summer solstice (typically June 21) through to the autumnal equinox (typically September 21).

The Arctic experiences some days in summer when the Sun never sets, and some days during the winter when it never rises

Countries covered by the Arctic hemisphere. Arctic ( /ˈɑrktɪk/ or /ˈɑrtɪk/) is a polar region located at the northern-most part of the Earth. The Arctic consists of the Arctic Ocean and parts of Canada, Russia, Denmark (Greenland), Norway, the United States (Alaska), Sweden, Finland, and Iceland.