Fire Scars in Australia's Simpson Desert
Bright orange fire scars show up the underlying dune sand in the Simpson Desert, 300 kilometers east of Alice Springs. The background is an intricate pattern of sand cordons that angle across the view from lower left to upper right. These cordons are now mostly green, showing that, although they were once shifting, they have become more or less static--"tied down" by a vegetation mat of desert scrub.
The fire scars were produced in a recent fire, probably within the last year. The image suggests a time sequence of events. Fires first advanced into the view from the lower left--parallel with the major dune trend and dominant wind direction. Then the wind shifted direction by about 90 degrees so that fires advanced across the dunes in a series of frond-like tendrils. Each frond starts at some point on the earlier fire scar, and sharp tips of the fronds show where the fires burned out naturally at the end of the episode. The sharp edges of the fire scars are due to steady but probably weak southwesterly winds--weaker winds reduced sparking of additional fires in adjacent scrub on either side of the main fire pathways. Over time, the scars will become less distinct as vegetation grows back.