# Polar region- Variations in daylight hours

## Polar region– Variations in daylight hours

Question:-Polar regions experience extreme variations in daylight hours. Explain the phenomena behind this.

- The earth rotates around its own axis and revolves around the sun simultaneously. The two activities together with the inclined position of the axis of earth's rotation with plane of ecliptic results in the variations in length of day and night in different places.

- During June, summers over northern hemisphere, the tropic of cancer receives direct rays of the sun, causing longer days and shorter nights. The poles experience daylight for almost 6 months until the onset of winter.

- In this case, areas near the poles receive less heat since the sun rays are slanting. With the north pole inclined towards the sun places beyond the Arctic circle experience continuous daylight for about six months which is popularly known as 'Land of the Mid-night Sun'.

- As a large part of the northern hemisphere receives sunlight, regions north of equator experience summer and the longest day and the shortest night at these places occur on 21st June which is commonly referred to as the summer solstice.

- Revolution literally is the earth's motion in its elliptical orbit around the sun where one revolution is completed in 365 ¼ days. Here the angle of the axis is inclined to the place of ecliptic at 66 and half which gives rise to seasons. The length of day and night largely depends on the season and latitudinal position, however at the equator days and nights remain the same throughout the year.

Effects of latitude:

- Latitude is an angle which ranges from 0° at the equator to 90° at the south and north poles. 1' of latitude is almost equal to 111 km.

- Length of days is the same if regions are located on same latitude and different if they are on different latitudes. At latitude 0° ie the equator, length of the day will be approximately 12 hours whereas areas on the equator have a constant 12 hours of day throughout the year.

- As we move away from the equator towards the poles, north or south, length of the day receiving light increases to 24 hours in summer or decreases to zero hours of day light in winter.

Facts:

- Lines of latitude get shorter towards the poles and at the equator, the greatest circle.

- Antarctica is Earth's highest continent.

- 30% of the world's untapped oil reserves are located in the Arctic Circle.

- The South Pole sits on top of a thick sheet of ice, which in turn sits on top of a piece of land — Antarctica.

- The North Pole, on the other hand, is made up of a thin Arctic ice sheet that sits barely a foot above sea level — a fact that allows the landscape to absorb heat from the surrounding Arctic Ocean.

- Longitude and latitude are imaginary lines used to show location