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Introduction to ecosystems
Introduction to ecosystems

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Desert burrows

Look at the way in which the surface temperature of sand can change through a day (Figures 10 and 11).

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Figure 10 Temperatures below the sand surface on a dune in the Namib desert on a summer day
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This graph shows the temperatures (taken at 6 times a day: 4am, 8am, 12pm, 4pm, 8pm and 12am) below the sand surface on a dune in the Namib desert on a summer day. The X axis is labelled ‘sand temperature/degrees C’ ranging from 15 degrees to 45 degrees. The Y axis is labelled ‘sand depth/mm’ ranging from -300 mm to 0 mm. At -300 mm, all 6 times of day have sand temperatures of 32 degrees. On the surface however, at 4am the temperature is 16 degrees, at 8am the temperature is 17 degrees, at 12pm the temperature is 38 degrees, at 4pm the temperature is 40 degrees, at 8pm the temperature is 27 degrees and at 12am the temperature is 18 degrees. This graph shows the temperatures (taken at 6 times a day: 4am, 8am, 12pm, 4pm, 8pm and 12am) below the sand surface on a dune in the Namib desert on a summer day. The temperatures range from 15 to 45 degrees Celsius.

Figure 10 Temperatures below the sand surface on a dune in the Namib desert on a summer day
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Figure 11 Temperatures below the sand surface on a dune in the Namib desert on a winter day
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This graph shows the temperatures (taken at 6 times a day: 4am, 8am, 12pm, 4pm, 8pm and 12am) below the sand surface on a dune in the Namib desert on a winter day. The X axis is labelled ‘sand temperature/degrees C’ ranging from 15 degrees to 45 degrees. The Y axis is labelled ‘sand depth/mm’ ranging from -300 mm to 0 mm. At -300 mm, all 6 times of day have sand temperatures of 22 degrees. On the surface however, at 4am the temperature is 16 degrees, at 8am the temperature is 15 degrees, at 12pm the temperature is 31 degrees, at 4pm the temperature is 43 degrees, at 8pm the temperature is 26 degrees and at 12am the temperature is 18 degrees.

Figure 11 Temperatures below the sand surface on a dune in the Namib desert on a winter day

Although the temperatures of sand at various depths in the Mojave desert would not be precisely the same as those in the Namib, the physical characteristics and thermal environment provided by dry sand are broadly the same in all deserts at similar Ta.

A benign temperature is available below the surface at all times of the day in both seasons, in spite of extremes on the surface. These surface temperature extremes are not very different in summer and winter. The high afternoon surface temperature in winter is due to hot, dry winds (Berg winds) that reach the desert in the winter months.