Earth At Summer Solstice
June 21, 2002
The above GOES full disk satellite image, taken on June 19, shows the Earth's Western Hemisphere just before the summer solstice. The summer season in the Northern Hemisphere officially begins today (June 21) at 9:24 a.m. Eastern Daylight Time - also it's the day having the most daylight. At this time, the Northern Hemisphere is tilted toward the Sun. Note that the illuminated portion of the Earth slants from the upper left to the lower right. Thus, while the Arctic (north of 66 1/2 degrees north latitude) is now bathed in constant sunshine, it's dark in the Antarctic. At noon on the solstice, the Sun's rays are directly overhead the Tropic of Cancer (23 1/2 degrees north latitude). Also note the area of sunglint (brightened area) near the Tropic of Cancer in the Atlantic Ocean, northeast of the coast of South America. In eastern North America, it's early morning on this image, but it's still nighttime in the western part of the continent. However, north of about 55 degrees north latitude, even when the Sun sets, it never moves far below the horizon - it's always twilight.
There seems to be a high correlation between the illuminated portion of the Earth's disk and the presence of clouds. Of course, this is because the image was taken in the visible wavelengths, and clouds as well as features on the Earth's surface are rendered invisible at night.