Revolution and Rotation Effects on Earth's Atmosphere

Earth

• Earth’s surface is covered with a large portion of water which is about 71 % of its total surface and only 29 % is land which consists of land and islands. This land and islands too have water in the form of river, lake, ponds, well, ground water etc which also contributes in hydrosphere of Earth.
• Age of the Earth is about 4.54 billion years.
• Determination of Earth’s age: Scientists determine the age of the Earth through different methods few of them are mentioned below:

1.  Salinity of the oceans: In this method scientists determines the age of the Earth by calculating the amount of total salt present in the ocean then calculating how mush salt are being carried out by rivers into the ocean every year.
2. Erosion: Scientists observed a fact that the erosion of 1 foot takes place in every 5000 years. With this observation we can estimate the age of rock formations.
3. Sedimentation: In this method scientist used the technique of calculating the time of deposition of a fixed amount of sediments, then calculates the total amount of sediments deposited.
4. Radioactive Method: This method is most reliable method among all other methods. Scientists calculate the amount of Uranium present versus amount of lead present in the different rocks, as we know that half of the Uranium alters to lead in about 5 billion years. So by calculating this, scientists calculated the age of the Earth is 4.5 billion Years.
5. Carbon-14 dating: Animals have carbon 14 in them when they die. After their death no more Carbon-14 produced in their dead body, however Carbon-14 which are present in their body begins to decay. Hence by calculating the amount of Carbon-14 left versus amount of other substance present, Scientists can calculate the age of different rocks. Here it is to be noted that fossil remains are found in Sedimentary rocks and not in Igneous and Metamorphic rocks. So by this method age of rock can be determined up to 15000 years old only. Radioactive method can be used for even older rocks.

• Tilt of Earth’s Axis: Earth’s axis is tilted and it makes an angle of 66 ½ degree with the plane of ecliptic, and 23 ½ degree from the line perpendicular to the plane. One more thing here to be noted that this tilt of axis of Earth is constant and Earth remains tilted in the same position while it rotates or revolve around the sun. Its North Pole constantly points towards the Pole Star or Polaris and this phenomenon is called as parallelism of the axis.

• Earth’s average revolution speed around the Sun is 18.5 miles per second or 29.6 km per second. This is average, because velocity of Earth around the Sun is not constant. It increases when it comes near to the Sun and decreases when go far away from the Sun.
• Revolution is having a unique effect on the earth on its atmosphere and physical condition few of which are mentioned below:
  1. Revolution of Earth around the Sun is one among the different reasons for the change of season of places on Earth.
  2. Due to revolution Earth positions and its tilt towards the Sun are continuously changing due to which different regions of the Earth also experiences different length of day and night.
  3. Due to revolution there is also a variation in the position of Sun overhead in the noon at a particular place over the year.
• Reasons for change of season on Earth: One important point I want to reveal that most of the student thinks that when Earth moves away from the Sun there is a winter season and when it reaches closer to the Sun there is a summer season on the Earth; this is absolutely not the reason. Earth is closest to the Sun on about 3^rd January every year however on 3^rd January there is chilling winter season in the northern hemisphere. Hence at any place seasons or we can say that atmospheric condition changes and repeats itself year after year. This is due to the following reasons:
  1. Rotation of the Earth on its axis and its revolution around the Sun in its orbit is one of the reason for change of season on the earth otherwise if the earth wouldn’t revolves and rotates then one part continuously receives Suns light and other part remains dark. So rotation and revolution of Earth are the main reason for day and night and change of season on the Earth.
  2. Tilt of Earth’s axis by 23 ½ degree from the plane of perpendicular is another main reason for change of season.
  3. As we know that Earth constantly points towards Polaris. Due to this reason in half of the year northern hemisphere of the Earth receives more Sun’s light and for rest half of the year southern part receives more Sun’s light.
• Solstice & Equinoxes: When the Earth revolve around the Sun, due to its constant tilted axis it occupies different positions. There are four different unique positions which Earth occupies while revolution around the Sun in a year. Two among them are solstice and other two are equinoxes. This two position have a great influence on the atmospheric condition or season of the Earth. Before understanding this Solstice and equinox it is very important to know the fact that Sun’s rays do not fall vertical on all points on the Earth at the same time; however Sun’s rays falls vertical only at particular latitude at a time on the Earth. Sun’s rays falls vertical on Equator on
  1. Summer Solstice: It occurs when the Sun’s rays falls vertically on Tropic of Cancer. This position occurs once in a year on 21^st or 22^nd of June. Due to this reason 21 Jun is chosen for international Yoga day. After 21 June Sun’s rays starts going down towards Equator. There is a summer season in Northern hemisphere. Day time increases in Northern Hemisphere and decreases in Southern hemisphere. Between Arctic Circle and North Pole day light lasts for 24 hours.
  2. Winter Solstice: It occurs when the Sun’s rays fall vertically on Tropic of Capricorn. This position occurs once in a year on 21^st or 22^nd of December every year. After winter solstice Sun’s rays starts moving upward towards equator. Duration of day time increases in Southern Hemisphere and decreases in Northern Hemisphere. There were day time of 24 hours between Antarctic Circle and South Pole and night of 24 hours between Arctic Circle and North Pole. During this period Southern Hemisphere of Earth receives maximum Sun light or Sun’s energy. There is summer season in Southern hemisphere. That’s why Christmas is celebrated in summer in Australia.
  3. Equinoxes: It occurs twice in a year on March 20^th or 21^st and September 22^nd or 23^rd. During Equinoxes Sun’s rays falls vertically on Equator and due to this reason day and night in both the hemisphere is of equal duration i.e., 12 hours. Again this two equinoxes on different dates of year are same but they are known by different names. They are:
     1. Vernal or Spring equinox: It occurs on March 21^st or 22^nd
     2. Autumnal equinox: It occurs on 22^nd or 23^rd