Spring and Summer

Julia Swain
Weather Science
10/15/98

Seasons are produced by the inclination of the earth’s axis of rotation, with the yearly revolution around the sun. During the earth’s yearly revolution around the sun, the northern and southern hemispheres alternate their incline towards and away from the sun. This unequal heating of the earth’s surface causes the weather to change in approximately three-month periods. When the Northern Hemisphere is inclined toward the sun from about March 21st to September 23rd the earths surface is heated causing the seasons of spring and summer to occur. Meanwhile in the Southern Hemisphere the effects of fall and winter occur. The first three months are the season of spring and the second three months are the months of summer.
The vernal equinox occurs when the sun is directly over the equator and it complies with the first day of spring. It also means that the sun is an equal distance from the north and south poles. At this time both hemispheres have the same amount of sun as the sun makes its way north. Before the vernal equinox the sun hits the northern surface at an angle instead of hitting it directly. By hitting the earth’s surface at an angle there is not as much radiation warming the surface. As the earth rotates and the sun moves further north the temperature increases and the weather turns warmer. During the three months of spring the sun continues to move north and warming the earth more efficiently. At around June 21st the sun is directly facing the tropic of cancer. At this time the movement north comes to a halt and the earth’s surface is at its warmest point, the summer solstice. It is also known as the longest day of the year when the earth is furthest away from the sun. During the winter the sun is actually closer to the sun, but it gets less heat because of the unstable amount of radiation. Throughout the spring months the sun is slowly making its way to its maximum power on the first day of summer. The earth stays warmer during the summer months even when the sun is moving south because it is moving downward at a slower pace than its speed moving up to the north. The Southern Hemisphere has the exact opposite seasons. At the time of the vernal equinox or northern spring it is the beginning of fall. As the summer solstice makes its decent into fall in the north the Southern Hemisphere is beginning their spring season. It can be a slow and unpredictable process, the weather can be calm one year and vicious the next.
Inside the Arctic and Antarctic circles the weather is dramatically different then from the rest of the earth’s surface. During the summer solstice in the Northern Hemisphere the North Pole will receive 24 hours of daylight. At its greatest altitude in the sky the sun will be visible for a full 24 hours. During these 24 hours the sun will appear in the same spot for a few days. Slowly the sun will begin to set for a few minutes at a time. So there are a few months where the days will increase in length then they will start to decrease in length. During the winter there are a few days in which the sun never rises, causing darkness for days at a time. In the South Pole the Antarctic Circle gets the same seasonal change at the opposite time as the north. During the few days when there is only sunlight in the Arctic Circle there will be a few days of only darkness in the Antarctic Circle. The angle of the earth and its rotation prevent either of the poles from getting hit directly be the sun. The sun will hit it at an angle that changes so slightly during the summer solstice that the poles will have only sunlight for 24 hours at a time.
The season on earth are caused by the earth’s angle of rotation around the sun. It is estimated that the sun will be at its highest point during the day of June 21st, however it is not exact. It is hard to predict the weather for a certian season because each year