Give reasons for the following : - (a) Twilight is of longer duration in higher latitudes than at Equator.
Give reasons for the following : -
(a) Twilight is of longer duration in higher latitudes than at Equator.
(b) Altitude of the Sun varies at a place according to seasons.
(c) Seasons are reversed between Northern and Southern Hemisphere.
(d) The duration of day and night is equal everywhere in the world on 21st March.
(e) Tropical latitudes are the hottest part of the’Earth.
(f) The period of Twilight and Dawn increases polewards.
(g) 25th of December (Christmas) in New Zealand may be one of the hottest days of the year.
(h) Noon is hotter than morning.
(i) Vertical rays are hotter than slanting rays.
(j) There is no Twilight and Dawn on the Equator.
(k) Sun rises on the east.
(l) Norway is called the land of the Midnight Sun.
(m) The speed of the rotation of the earth is greater at the Equator than at the Arctic Circle.
(n) Winds are deflected to the right in Northern Hemisphere and to the left in Southern Hemisphere.
(o) The variation in the lengths of day and night goes on increasing polewards.
1 Answers
(a) The duration of twilight at a place depends on the path of the Sun in the sky. In the low latitudes, where the Sun’s path is almost vertical, the duration of twilight is short. The Sun sinks below the horizon rapidly. In the middle and high latitudes the duration of twilight is long because at these latitudes the Sun has an inclined path.
(b) The altitude of the mid-day sun is related to the latitude of a place. Because of seasonal changes in the altitude of the sun at different latitudes, the altitude of midday sun also varies.
(c) The 23.45° tilt between the equator and the orbital plane causes each Hemisphere to lean towards the sun for part of the year. So seasons are reversed between the two Hemispheres.
(d) On March 21 rays of the sun fall vertically on the equator, and because of inclined axis of the earth, the circle of illumination passes through the two poles resulting in equal duration of day and night all over the world.
(e) Tropical latitudes are the hottest part of the Earth, because the belt between Tropic of cancer and Capricorn is the migration belt of the Sun in which the Sun remains overhead on one or another place which naturally receives the maximum heat of Sun.
(f) Latitudes go on increasing polewards. In the middle and high altitudes duration of sunlight is limited. Both twilight and dawn continue so long as the sun is 18° below the horizon. Duration of twilight and dawn is especially large beyond 50° latitude.
(g) New Zealand is located at 40° latitude. On 22 December sun is in the Southern Hemisphere (Winter Solstice). So December 25 may be one of the hottest days of the year in New Zealand.
(h) At noon sun rays fall vertically overhead covering shorter distance than the slanting rays of the morning.
(i) Vertical rays remain focussed over a shorter area than slanting rays. During slanting rays solar radiation is spread over a larger area.
(j) The Twilight and Dawn depend on the path of the sun in the sky. At the Equators, sun’s path is almost vertical. So duration of twilight and dawn combine with sunset and sunrise.
(k) Earth rotates from west to east, which makes us see sun rise from the east.
(l) The good part of Norway is situated North of the Arctic Circle where duration of daylight goes on increasing from 24 hrs to six months poleward.
(m) Earth is spherical in shape and its circumference is greater at the equator than at the Arctic Circle.
(n) Earth spins west to east in inclined position. The deflection of moving air streams, known as Coriolis Force, is produced because earth beneath moves.
(o) It is because circle of illumination is widest at the equator and goes on decreasing towards the poles.