Reading the book "Ice Age" by John & Mary Gribbin, was really revealing. In this book author have put some light on continuously fluctuating climate of earth. One of the factor mentioned is Earth's movement in space, on its axis, around barycenter, around sun. Barycenter is the center of gravitational center between Earth and the Moon. In layman's language, it will be balancing point of a seesaw, if we put Earth on one side and Moon on other. This center, as you might have already guessed, lies about 1,000 miles (1,600 kilometers) below Earth's surface. Earth rotates on its axis, wobbles around pericenter like a spin top, changes its angle of inclination, revolves around the Sun in an elliptical orbit. This orbit also changes its ellipticity as Sun changes its position from center of ellipse to move in one side. Maximum change in ellipticity in Earth's orbit is considered when Sun moves from the center around five percent of distance between apogee and perigee. Current ellipticity is one percent. After considering all these movements, frequency of ice age comes around 1,00,000 for large cycle and around 11,000 years for smaller cycle.
Still, there are many other motions of Earth which are still not considered in this equation. For example, our solar system itself is moving towards Cygnus constellation, having Denab and one black hole. Our solar system is also revolving around milky way galaxy's center, addition to this solar system is also spinning in and out of milky way plane. Milky way itself is moving. These motions were neglected as it was considered that they don't have much impact on Earth's climate and also at that time, without the computers calculating their effect was too cumbersome. Out of these motions, revolution of solar system around milky way center has a time period of 220 million years. These motions don't have any effect on the heat recieved by the Earth from the Sun but as the equation pointed out that hot summers or cold winters don't make much difference but its the cold summers and warm winters do the trick.
Total heat recieved by the Earth from the Sun doesn't vary much from any of Earth's motion but its the cooling off which varies as the winters or summers enlongate. As per this assumption, even a small change in the Earth's position result in climate variations. One more factor which decide, how much heat will be absorbed by the Earth is which part of Earth is facing Sun. Right now, Earth is tilted 23 and 1/2 degree on its asix, so, parts of the Earth which face direct sunlight lie on 23 1/2 degree North and South latitudes. If this latitude area is covered by land then it will absorb more heat than if it's water. So, here continental plates movement also play a part in climate change.
Outer space, as for simplifications, is considered vacuum but which is not so. Space is filled with rocks, small debris, dust, gases, photons and many other smaller particles. In absolute conditions, outer space temperature should be zero kelvin, but studies have shown that it minimum tempearature lies around 3 degree kelvin. Depending on the distance of the point from nearby stars, size of the the stars, total radiation emitted by the stars temperature will increase. Thus, any change in the position of the solar system will result in slight change in temperature in surrounding space. It will be due to not only Sun but also other nearby stars. This change may result in increase or decrease in rate of colling of Earth. Though I agree, that the difference in temperatures between Earth's atmosphere and outer space is so large that any small change in the space temperature may not have any significant impact.
Other factor which may have some impact is effect of meteors entering the Earth atmosphere. Everyday, we have more than 1,00,000 meteors entering Earth's atmosphere. Out of which very few rocks complete the journey to the Earth's surface. Any temperature change due to this bombardment of debris is ruled out as too minute but what if the rate of bombardment increases manifold? As the Sun keep spinning in and out of the plane on which bulk of the Milky Way galaxy lies, it is apparent that when Sun passed through this plane's axis frequency of meteors falling on Earth will go up. At present, Sun is away from the plane axis but when it will move near the axis, bombardment rate will rise tremendously. Meteors, also have the other effect of increasing particle density in Earth's atmosphere. Again, the impact on climate will be very minute but may not be insignificant.
Still, there are many other motions of Earth which are still not considered in this equation. For example, our solar system itself is moving towards Cygnus constellation, having Denab and one black hole. Our solar system is also revolving around milky way galaxy's center, addition to this solar system is also spinning in and out of milky way plane. Milky way itself is moving. These motions were neglected as it was considered that they don't have much impact on Earth's climate and also at that time, without the computers calculating their effect was too cumbersome. Out of these motions, revolution of solar system around milky way center has a time period of 220 million years. These motions don't have any effect on the heat recieved by the Earth from the Sun but as the equation pointed out that hot summers or cold winters don't make much difference but its the cold summers and warm winters do the trick.
Total heat recieved by the Earth from the Sun doesn't vary much from any of Earth's motion but its the cooling off which varies as the winters or summers enlongate. As per this assumption, even a small change in the Earth's position result in climate variations. One more factor which decide, how much heat will be absorbed by the Earth is which part of Earth is facing Sun. Right now, Earth is tilted 23 and 1/2 degree on its asix, so, parts of the Earth which face direct sunlight lie on 23 1/2 degree North and South latitudes. If this latitude area is covered by land then it will absorb more heat than if it's water. So, here continental plates movement also play a part in climate change.
Outer space, as for simplifications, is considered vacuum but which is not so. Space is filled with rocks, small debris, dust, gases, photons and many other smaller particles. In absolute conditions, outer space temperature should be zero kelvin, but studies have shown that it minimum tempearature lies around 3 degree kelvin. Depending on the distance of the point from nearby stars, size of the the stars, total radiation emitted by the stars temperature will increase. Thus, any change in the position of the solar system will result in slight change in temperature in surrounding space. It will be due to not only Sun but also other nearby stars. This change may result in increase or decrease in rate of colling of Earth. Though I agree, that the difference in temperatures between Earth's atmosphere and outer space is so large that any small change in the space temperature may not have any significant impact.
Other factor which may have some impact is effect of meteors entering the Earth atmosphere. Everyday, we have more than 1,00,000 meteors entering Earth's atmosphere. Out of which very few rocks complete the journey to the Earth's surface. Any temperature change due to this bombardment of debris is ruled out as too minute but what if the rate of bombardment increases manifold? As the Sun keep spinning in and out of the plane on which bulk of the Milky Way galaxy lies, it is apparent that when Sun passed through this plane's axis frequency of meteors falling on Earth will go up. At present, Sun is away from the plane axis but when it will move near the axis, bombardment rate will rise tremendously. Meteors, also have the other effect of increasing particle density in Earth's atmosphere. Again, the impact on climate will be very minute but may not be insignificant.
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