Changes

=== Angle of Sun's Radiation ===

=== Angle of Sun's Radiation ===

Axial tilt of the earth results in there being a difference in how much sunlight reaches a given point on the earth's surface during the course of a year. The angle at which sun's radiation falls on the earth influences seasonal temperatures.  

Axial tilt of the earth results in there being a difference in how much sunlight reaches a given point on the earth's surface during the course of a year. The 23.5 degree tilt changes the angle of incident sunlight influencing the earth's temperatures thereby causing cold, heat or optimum levels of climatic conditions. The angle of Sun's radiation varies across locations at different latitudes. When the Sun's rays strike the Earth's surface near the equator, the incoming solar radiation is direct (nearly perpendicular). Hence solar radiation is concentrated over a smaller surface area, causing warmer temperatures. At higher latitudes, the angle of the impacting solar radiation is small causing the radiation to spread over a larger surface area and cooler temperatures. Latitudes play an important role in governing surface temperature. <ref>https://mynasadata.larc.nasa.gov/print/pdf/node/87</ref>

 

One of the major differences in changing seasons is the length of the days and this is affected by the earth's tilt. The hemisphere tilted toward the sun receives more direct rays of sunlight as well as higher number of daylight hours than the hemisphere that is tilted away from the sun. Surface temperatures on an average are warmer at lower latitudes and cooler at higher latitudes even though higher latitudes have more daylight hours during the summer months.<ref>https://www.ces.fau.edu/nasa/module-3/why-does-temperature-vary/seasons.php</ref>

 

Climatic and weather conditions also affect the seasonal changes apart from the above aspects. The Sun's energy input drives climate but the atmosphere also plays an important role. Refraction of light by the atmosphere influences its distribution over the surface of earth. Similarly heating is most intense near the equator, where sun's rays come down steeply. The patterns of heating further influence the heating and cooling of oceans thereby setting in climatic patterns. As heat diffuses through the layers of the atmosphere, it is also spread by atmospheric flows, by winds. Large scale air flows near the tropics and to the equator.<ref>https://pwg.gsfc.nasa.gov/stargaze/Sweather2.htm</ref>

== Classification of Seasons ==

== Classification of Seasons ==