What causes the seasons?
During part of the year, Earth is closer to the sun than at other times. However View of Earth in relation to sun It is winter in December in the Northern Hemisphere, because that is when it is the South Pole's turn to be tilted toward the sun. The Sun's rays strike the surface most directly at the equator. The seasons are caused by the direction Earth's axis is pointing relative to the Sun. solstice in the Northern Hemisphere, it is winter solstice in the Southern Hemisphere. The winter solstice in the Southern Hemisphere is June 20 or 21, while the flat disc where most objects in the solar system orbit the sun. Earth's axis is In June , when the Northern Hemisphere is tilted toward the sun, the sun's winds of the Indian Ocean and South Asia, which often bring heavy rains.
This day is known as the Summer Solstice. The same happens on December 21st at the Tropic of Capricorn. Circulation of Atmosphere Equalization of temperature is air that circulates through the atmosphere within cold and warm fronts.
Seasons and Climate
With the help of these fronts, precipitation reaches areas further away from water masses. The Hadley-Ferrell Model was a particular atmospheric model that incorporates three counter-rotating, compensating cells for the north and south hemispheres.The Globe Earth - Sunrise & Sunset Animated
These cells consist of moving air masses, which eventually create rainfall and other forms of weather. From north to south, they turn as follows: As you can tell, starting at the equator is the Hadley cell in which warm air converges and rises, which formulates a low pressure.
Then there is the Ferrel cell, which consists of high pressure and descending air. Finally is the Polar cells that correspond to the North and South Poles, which are very cold with high-pressure, hence the Polar front.
This is the Hadley-Ferrel Model. Land heats up and cools down faster than water. This explains why temperatures are so extreme here in Nebraska landlocked, with no ocean to absorb heat. When it is summer in the Northern Hemisphere, it is winter in the Southern, and vice versa.
Tropics[ edit ] The tropical and subtropical regions see little annual fluctuation of sunlight. As a result, the amount of precipitation tends to vary more dramatically than the average temperature. When the Zone is north of the Equator, the northern tropics experience their wet season while the southern tropics have their dry season.
This pattern reverses when the Zone migrates to a position south of the Equator. Mid-latitude thermal lag[ edit ] In meteorological terms, the solstices the maximum and minimum insolation do not fall in the middles of summer and winter. The heights of these seasons occur up to 7 weeks later because of seasonal lag.
Sun Earth Relationship
Seasons, though, are not always defined in meteorological terms. In astronomical reckoning by hours of daylight alone, the solstices and equinoxes are in the middle of the respective seasons. Because of seasonal lag due to thermal absorption and release by the oceans, regions with a continental climatewhich predominate in the Northern Hemisphereoften consider these four dates to be the start of the seasons as in the diagram, with the cross-quarter days considered seasonal midpoints.
The length of these seasons is not uniform because of Earth's elliptical orbit and its different speeds along that orbit.
Accordingly, if floral activity is regularly observed during the coolest quarter of the year in a particular area, it is still considered winter despite the traditional association of flowers with spring and summer. Additionally, the seasons are considered to change on the same dates everywhere that uses a particular calendar method regardless of variations in climate from one area to another. Most calendar-based methods use a four-season model to identify the warmest and coldest seasons, which are separated by two intermediate seasons.
This path that the earth takes to revolve around the sun is called the elliptical path. When the sun is moving down from above the celestial equator, crosses it, then moves below it, that point of intersection between the two planes is when the Autumnal Equinox occurs.
This usually happens around the 22nd of September. When the Sun moves up from below the celestial equator to above it, the point of intersection between the sun and the celestial equator is when Spring Vernal Equinox occurs. It usually happens around the 21st of March. During the equinoxes, all parts of the Earth experiences 12 hours of day and night and that is how equinox gets it name as equinox means equal night. At winter solstice Decthe North Pole is inclined directly away from the sun.
At this point it will be at declination This cycle will carry on, creating the seasons that we experience on earth. The earth is tilted At the summer solstice which occurs around 21st of June, the North Pole is pointing towards the sun at an angle of Therefore the apparent declination of the sun is positive At the Winter solstice which occurs around 21st December, the North Pole is pointing away from the sun at an angle of