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.