Four Seasons

by Jon Burch Photography

Title

Four Seasons

Artist

Jon Burch Photography

Medium

Photograph - Digital Capture

Description

In northern Colorado, we have four seasons. Almost winter, winter, still winter and construction! Maybe I should add a fifth season and call it 'Fire'!

Over the course of a year, as the Earth travels around the Sun, the Earth's 23.5 degree tilt on its axis remains constant. The north part of this axis of rotation currently points toward the north celestial pole located close to the star Polaris in the constellation Ursa Minor or Little Dipper. Because of this constant tilt of the Earth's axis and the stationary point of the North Celestial Pole near Polaris, as the year goes on, the amount of solar insolation received by any location between the two tropics, Cancer and Capricorn, varies with the season. (The Tropic of Cancer is 23.5 degrees north of the Earth's equator and the Tropic of Capricorn is 23.5 degrees south.)

For example, in the northern hemisphere summer, the solar insolation or solar heating amounts to about 1000 watts per square meter but during the winter, it is only about 460 watts per square meter. When the Sun is nearer the horizon in the winter, less insolation is received by the ground and during the summer, when the sun is higher in the sky the opposite is true. This difference causes the ground to heat up and cool down with the seasons as the Sun appears to climb higher in the sky. If you are on the equator, or anywhere between the two tropics, the Sun will be directly overhead twice each year as the Earth completes its orbit. If you happen to be ON either the Tropic of Cancer in the northern hemisphere or ON the Tropic of Capricorn in the southern hemisphere (23.5 degrees north and south of the equator respectively), the Sun will be at your zenith only once each year. For those of us living north of the Tropic of Cancer, it is impossible for the Sun to ever be directly (90 degrees) overhead. The higher above the horizon the Sun gets, the greater amount of heating.

In addition to this varying amount of heat available for the ground to soak up, during the course of a year the proximity of the Earth to the Sun also changes due to our elliptical orbit. Contrary to the belief of many, the seasons are not caused by how far or how close the Earth is to the Sun. In fact, we are actually closer to the Sun during the month of January and further away during the month of July. It is the angle at which the Sunlight strikes the ground that causes the seasons - distance doesn't really matter much. (In the northern hemisphere, we actually receive about 7% more solar insolation in January than we do in July)

During the transitional times of the year, spring and autumn, any given location on the Earth may experience sunlight, rain, snow and/or hail separately or nearly at the same time depending upon the local conditions. Road construction is another constant in most places.

In February, when this image was made, Sedona not only had some snow on the ground, but also some clouds in the sky, plus a little bit of sunlight hitting parts of the red rocks themselves. These characteristics too, vary during the day. In the tiny fraction of a second during which this image was made, several different seasonal characteristics can be seen in and around the Sedona's red rocks.

The red rocks of Sedona show layers of time in the rocks. Defining the boundary between the Colorado Plateau to the north, the Basin and Range to the south and the base of the Mogollon Rim, Courthouse Butte, Bell Rock and the other red rocks form a cliff that runs east-west through the middle of Arizona. In the Sedona region, erosion has gradually eaten away at the Mogollon rim, moving it northward a distance of about four miles and leaving behind some of the most spectacular and picturesque canyons and buttes found anywhere in the world. Even during construction season!


Image copyright 2013 Jon Burch Photography

Uploaded

March 17th, 2013

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