GOLF 4-3-9 Antarctica Expedition 2008
Report -- Monday 08 December 2008 -- The Sun is Always Up!
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GOLF 4-3-9 Antarctica Expedition 2008 |
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Here in the McMurdo area of Antarctica the sun stays up 24 hours a day this time of year. Laurie took photos of the Mountains across McMurdo Station four times throughout the day so you can see that it is always daylight. The amount of solar energy that falls on a specific location can help us determine what sort of microbial community might be active there. To determine the amount of solar energy that hits a spot we start with something called hemispherical photography. A photograph is taken with a fish-eye lens pointing straight up. Then the true horizon is marked in (the clouds removed from the picture and the snow painted black so there is no confusion between sky and land). Since we know the exact location where the photo was taken, we can calculate the suns path on any given day using a computer program. After that we can calculate the amount of solar radiation that hits the spot during a day or even over the entire year.
As an example of the suns path, we took a photo of the full sky in the Dry Valleys at one of Laurie’s previous field sites and one in Laurie’s hometown, Old Town, Maine. See this PDF File for the sun path difference between Maine and the Dry Valleys Antarctica. We also took photos of each cardinal direction so we can better assess any obstructions (like buildings in Maine or glaciers in Taylor Valley) that may change the amount of sunlight that hits a particular spot.
The sun path in Maine shows that the days are quite short in December, but in Antarctica, the sun never goes down (look at the green line)! It gives the phrase "burning daylight" new meaning. Just because the sun is not below the horizon does not mean that we can’t tell the difference between different parts of the day. During the "night" the light is less intense and it is often colder while mid-day it may be warm enough in the summer for ice to melt on the surface and small streams to flow through the streets of McMurdo. The chart shows that between April and September there is NO direct sunlight in Taylor Valley at all. Enjoy the sunlight while you can ...
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