In June, in the northern hemisphere summer, the Sun's rays — and warmth — reach all the way to the north pole. In December, in the northern hemisphere winter, the north pole is tilted away from the incoming sunshine. It also means that the angle at which sunlight strikes different parts of Earth's surface changes through the year.
Areas that receive more scattered sunlight receive less energy from our Sun. All of these factors combine to give Earth its annual cycle of seasons!
For part of our orbit the northern half of Earth is tilted toward the Sun. This is summer in the northern hemisphere; there are longer periods of daylight, the Sun is higher in the sky, and the Sun's rays strike the surface more directly, giving us warmer temperatures. The north pole is in constant daylight! When the northern half of Earth is tilted toward the Sun, the southern hemisphere is tilted away. People in the southern hemisphere experience the shorter day lengths and colder temperatures of winter.
During winter in the northern hemisphere, our northern axis continues to point to the North Star, but, because we have moved in our orbit around the Sun, our northern hemisphere now points away from our Sun. The north pole is completely dark and other places in the northern hemisphere experience the shorter day lengths and colder temperatures of winter as the Sun traces a lower arc across the southern sky and the Sun's rays strike the surface at a lower angle.
When it is winter in the northern half of Earth, the southern hemisphere, tilted toward our Sun, has summer. During fall and spring, some locations on Earth experience similar, milder, conditions.
Earth has moved to a position in its orbit where its axis is more or less perpendicular to the incoming rays of the Sun. The durations of daylight and darkness are more equally distributed across all latitudes of the globe. What doesn't cause the seasons? The seasons are not caused by how far Earth is from our Sun. Earth's orbit around our Sun has a slightly elliptical path very slight! This means that, during the year, Earth is sometimes farther from our Sun, and sometimes closer — but the difference is small not so for some other planets!
Earth is closest to our Sun in January perihelion and the farthest away in July Earth is If distance were the most important factor, the entire Earth would have summer in January when we are closest to our Sun and winter in July when we are farthest away!
What are solstices and equinoxes? Solstices occur when Earth's axis is pointed directly toward our Sun. An upper M1 or M2 molar of the bovid Supplementary Fig. Each sample was split into two specimens. The first set of specimens was analyzed without pre-treatment and the second set was leached in order to remove soluble carbonates. The isotopic composition of the non-leached and leached samples from the bovid tooth are presented in Supplementary Table 4.
The isotopic composition of the leached and non-leached samples yields the same general trends, suggesting a low diagenesis effect. Conditions at ca. Five replicates from each sample were measured. The resulting CO 2 was first purified and then analyzed.
Background with no gas in the ion source was not determined. An acid fractionation factor of 0. Each sample was analyzed in five replicates, corresponding to a shot-noise limit of 0. Whenever the external reproducibility 1 sdev was better than 0.
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The Equator , or line of 0 degrees latitude, divides the Earth into the Northern and Southern hemispheres.
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