By Amy Thompson
This page was created to satisfy an assignment for an Earth Science
lab, ES111. It was written in connection with Chapter 13, "Seasons,"
found within: Johnston, P., Aber, S.W., & Ye, H. (1996). Introduction to
earth science lab. Edina, MN: Burgess Publishing.
The year is divided in to four different quarters, and each quarter is named
to be a season that lasts about three months. The seasons are Spring, Summer, Autumn,
and Winter, with the start of each season noted as vernal equinox,
summer solstice, autumnal equinox, and winter solstice. Each season is marked by
different characteristics and affects. Throughout this web page you will
have the opportunity to learn about how and why the change
in seasons occurs and how seasons vary.
First I will give you a brief explanation about what causes the change in the
seasons. The seasons depend on how the earth is positioned with comparison to the
sun. The rotation and revolution of Earth about the Sun are two of the factors
responsible for seasons. The third reason for seasons has to do with the inclination
or tilt of the Earth's axis from the perpendicular to the plane of rotation.
When the Northern Hemisphere is tilted toward the sun, the Northern
Hemisphere receives direct sunlight. The most daylight hours in the Northern Hemisphere
happen at this time of the year, which is the time of Summer Solstice. When the
Northern Hemisphere is tilted away from the sun fewer daylight hours occur,
less direct rays of the sun, and this is called Winter Solstice.
During all these stages the lengths of daylight will be different. Except two
days during the year when an equinox occurs. During these two days neither hemisphere
is tilted toward or away from the sun, and the vertical rays of the sun are striking
the equator. This causes the hours of day and night to be equal all over the world.
The time of equinox is March 20 or 21 and September 22 or 23. The March equinox
represents the first day of Spring and is also called the Vernal Equinox. The
September equinox is the first day of Autumn or Fall and is also called
Autumnal Equinox. Find out a little more about each season below as it is
experienced in the northern hemisphere.
Spring is the first new season of the year and occurs during the months of
late March, April, May, and early June. The climate during this season varies from
mildly cool to warm. Spring is the transformation from Winter to Summer. Winter
snow is melting and temperatures are gradually getting warmer.
During this time many flowers and trees and beginning to bloom, while animals are
coming out of hibernation. Spring is a very beautiful season, full of color and
life.
Summer is the hottest season of any during the year. The Northern
hemisphere, where Emporia, Kansas is located, is tilting toward
the sun causing direct rays of the sun to warm the Earth and provide
long days. Summer occurs during the months of late June, July, August,
and early September. During Summer the days are longer because of the direct
rays focused on the northern hemisphere and the sun is at a very high
position in the sky.
Autumn is a very beautiful and colorful season that represents the change
between Summer and Winter. Autumn begins at the end of September and goes
through late December. There are a lot of changes with the arrival of
Autumn, from the holidays we celebrate to a variety of climate changes.
It often goes from warm and sunny to cold and rainy in a matter of hours.
Because of cooler temperatures and shorter days, the leaves on the trees
begin to change colors and fall from the trees. As a response to the cold
weather, as we get closer to Winter, continental water bodies and the Earth
begin to freeze. Birds, marine life, and some people migrate south during
this time!
Winter is the coldest and darkest season of the year. Winter occurs during the
months of December, January, February, and early March. The cold of Winter happens
as the Northern Hemisphere tilts away from the sun, which creates shorter daylight
hours. With less sun light to warm the Earth, a much colder climate results. During
Winter any precipition is likely to freeze, and fall in the form of ice and snow
because of lower temperatures. During Winter, the ground and plants will
freeze. This is the reason why animals hibernate during this period with their
stored food. Winter snow fall and temperatures vary from year to year and within
different temperate zones.
For additional seasonal information, visit some of these external web sites:
Von Del Chamberlain from Utah has a
Vernal Equinox site
called Looking Around or another site comes from the class notes of Prof. Lesikar,
Vernal Equinox
Prof. Lesikar's Astr 106 class notes on the
Autumnal Equinox from St. Cloud State
or another site
Looking Around by Von Del Chamberlain
If you have any questions or comments about this web-page please Email me at:
web page created September 26, 1998
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