Alaska is underlain by discontinuous permafrost meaning that there are areas with and without permafrost. Read this post to be able to recognize permafrost when you see it on your Alaska vacation or visit and to know what it is.
- Permafrost Facts
- How to Recognize Permafrost in the Taiga
- Recognize Permafrost when You Look at Constructions
- Further Alaska Phenomena You Should Recognize
- OOTD – Alaska summer work outfit
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Permafrost Facts
Alaska like most areas in high latitudes or many areas at high altitude has large areas of continuous or discontinuous permafrost. Permafrost or so-called cryotic soil is defined as soil that remains at temperatures at or below 32F (0oC) for two or more consequent years. Permafrost occurs on 24% of the land in the Northern Hemisphere. It also occurs on the ocean floor of the shelf of the Arctic Ocean. Permafrost holds about 0.22 per mille of the Earth’s total water.
How to Recognize Permafrost in the Taiga
The active layer is a layer that thaws in spring and re-freezes in fall. Due to the permafrost underneath, water can not percolate in deeper than the bottom of the active layer. Thus, trees growing on permafrost cannot root deep. Consequently, in these areas, spruce trees look very under-nutritioned and remain small (see photos above and below). Often only blueberries or scrubs can grow. The ground may be very moist during summer.
Recognize Permafrost when You Look at Constructions
When you build a house, street or path on permafrost, the construction conducts heat thawing some of the ground underneath. The melt-water may evaporate or run away laterally. Since the water originally was part of the soil matrix, the ice loss leads to shrinking of the ground thickness. The construction sinks and may deform.
See how this house's roof looks like the back of a dachshound due to permafrost thawing underneath. #permafrostthawing #Alaska Click To Tweet
Best practice is to avoid construction on permafrost or provide good insulation to the ground and/or build on stalks.
When there is a large ice-lens in the permafrost, a large whole can form seemingly over night when the thawed water finds a way to escape. Thawing permafrost destroys the parking lot at the Geophysical Institute on UAF campus on a regular basis.
When you visit Alaska, you will also see many powerline pols and street lamps affected by permafrost.
Further Alaska Phenomena You Should Recognize
Interested in discovering other Alaska phenomena like how to recognize a geological fault when you see it?
Do you want to know why the light is pink in Alaska in January?
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OOTD – Alaska summer work outfit
This outfit features a sheath dress dressed down with an utility jacket and low heel pumps. The scarf adds a pop of color, but picks up the color of the jacket and pumps. Thus, the color becomes part of the look that overall has a neutral feel color wise. More on styling non-boring looks with neutrals.
References
Mölders, N., and Romanovsky, V. E. (2006), Long-term evaluation of the Hydro-Thermodynamic Soil-Vegetation Scheme’s frozen ground/permafrost component using observations at Barrow, Alaska, J. Geophys. Res., 111, D04105, doi:10.1029/2005JD005957.
Mölders, N., Kramm, G. (2009). Permafrost modeling in weather forecasts and climate projections. New Permafrost and Glacier Research. 51-88.
Photos: N. Mölders, G. Kramm
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