Summer happens in the hemisphere tilted towards the Sun, and winter happens in the hemisphere tilted away from the Sun.
Click on image for full size
Windows to the Universe original image
Earth's Tilt Is the Reason for the Seasons!
The Earth travels around the Sun one full time per
year. During the year, the seasons change depending on the amount of sunlight
reaching parts of the Earth.
The seasons are caused because the Earth is tilted
23.5 degrees on its axis. Summer happens to the hemisphere tilted towards the
Sun, and winter happens to the hemisphere tilted away from the Sun. The hemisphere
that is tilted towards the Sun is warmer because sunlight travels more directly
to the Earth’s surface so less gets scattered in the atmosphere. That
means that when it is summer in the Northern Hemisphere, it is winter in the
Southern Hemisphere. The hemisphere experiencing summer, tilted towards the
Sun, has longer days and shorter nights than the hemisphere tilted away from
- On June 21st, the Northern Hemisphere is having its summer
solstice because it is tilted towards the Sun receiving the most direct
sunlight of the year during the longest day. The Southern Hemisphere is having
its winter solstice, the shortest day of the year, because it is tilted away
from the Sun.
- On December 21st, the Southern Hemisphere is tilted towards the Sun receiving
the most direct sunlight of the year during the longest day. The Northern
Hemisphere is having its winter solistice,
tipped away from the Sun, producing the shortest day of the year and a low
In general, summer and winter temperatures get lower the further you travel
from the equator. At the equator, there are no seasons because each day the
Sun strikes at about the same angle. Every day of the year the equator receives
about 12 hours of sunlight. The poles remain cool because they are never tilted
in the direct path of the sunlight. Light must travel through so much atmosphere
that much of it is scattered before reaching the Earth surface. During midwinter,
when a pole is tilted away from the Sun, there is no daylight at all at the
pole. The Sun never rises. However, during the summer, a pole receives sunlight
all the time and there is no night!
Shop Windows to the Universe Science Store!
The Fall 2009 issue of The Earth Scientist
, which includes articles on student research into building design for earthquakes and a classroom lab on the composition of the Earth’s ancient atmosphere, is available in our online store
You might also be interested in:
NASA's Earth Observatory has recently started making images of the entire surface of the Earth every month. There are no clouds in the images because they combine many pictures taken at different times...more
If Uranus is the "tilted planet", Mercury might be called the "upright planet". The spin axis of Uranus, which defines the locations of the planet's North and South Poles, is tilted by 98°. The spin axis...more
When the ground under your feet is frozen, interesting things can happen. The land may be covered with circles, polygons, or stripes, called patterned ground, which form as the land freezes. Trees may...more
Climate in your place on the globe is called regional climate. It is the average weather pattern in a place over more than thirty years, including the variations in seasons. To describe the regional climate...more
Leaders from 192 nations of the world are trying to make an agreement about how to limit emissions of heat-trapping greenhouse gases, mitigate climate change, and adapt to changing environmental conditions....more
Less than 1% of the gases in Earth's atmosphere are called greenhouse gases. Even though they are not very abundant, these greenhouse gases have a major effect. Carbon dioxide (CO2), water vapor (H2O),...more
Television weather forecasts in the space age routinely feature satellite views of cloud cover. Cameras and other instruments on spacecraft provide many types of valuable data about Earth's atmosphere...more