A polar day refers to a day when the sun does not set for 24 hours. This occurs because the top of the earth tilts toward the sun during one half of the year. Areas in the very northern and very southern parts of the globe are the only regions that experience both polar days and polar nights. Both of these phenomena often have negative effects on the few people who inhabit these regions.
Also referred to as the midnight sun, a polar day occurs when the sun does not set for an entire day, or 24 hours. It is called the midnight sun, because the sun is often still shining at midnight. This phenomenon can occur for just one day or six months, depending on how far away from the equator a region is.
The earth is tilted at a slight angle as it travels around the sun. This is sometimes referred to as an axial tilt, and this angle is responsible for the polar day. The northernmost part of the earth, which is the area north of an imaginary line called the Arctic Circle, is tilted toward the sun for six months of the year. The southernmost part of the globe, which is the area south of an imaginary line known as the Antarctic Circle, is also tilted toward the sun for six months. Since these areas are tilted toward the sun, the sun shines longer here during one half of the year, causing longer daylight hours, and even a polar day.
Depending on how far north or south from the Arctic or Antarctic Circles an area is, it can have anywhere from one polar day to six months worth of polar days. Regions that are right on these parallels of latitude will usually only experience just one polar day each year. The very top and bottom of the globe, on the other hand, will experience a six-month period when the sun never sets. When there is a polar day in the northernmost part of the globe, the southernmost part of the globe is usually experiencing a polar night.
The first polar day in the North Pole usually begins on the same day of the vernal, or spring, equinox, which occurs sometime around the 21st of March. Polar days then last until the autumnal, or fall, equinox, which occurs around the 23rd of September, and polar nights will begin. The sun is usually the highest in the sky at the time of the summer solstice, which occurs around the 21st of June. It is one this date, however, that areas right on the Arctic circle will experience a polar day.
Towns and villages that experience a polar day will typically celebrate the event. Festivals, for instance, are not uncommon. The 24 hours of sunlight is not always welcome by everyone, though. This constant light usually makes it very hard to sleep, leaving residents of these areas fatigued and irritable. The constant darkness of polar nights also has a negative impact on many people. This darkness can cause seasonal depression in many people.