Temperature inversion at 6000ft

[kala87]

I hope this is the right forum for this question - anyway, hear goes. One for the weather boffins!

Two weeks ago I was climbing out of an airport in the west of England in a BE76 Duchess, and encountered an apparent strong temperature inversion at alt 6000 ft. Surface temp. was 12C. There was a stable stratocu. deck between 2500 and 5000ft, with an indicated OAT of +1C in the tops. At 6000 ft the indicated OAT had jumped up to +10C!

I've encountered temperature inversions before, but a temperature of +10C at 6000ft in the west of England in early February is pretty impressive! I checked the OAT when we landed and it agreed with the ATIS temp. so nothing wrong there.

There was a stable high pressure system over the western UK at the time, so I assume the high OAT was due to compressional warming in a descending airmass.

At a TAS of only about 150 - 160kts RAM effect on the temp probe isn't going to be much, so I'm assuming the OAT was only slightly in error.

Any comments?

[bookworm]

Here are the soundings for what I think was the day you mean. Camborne is in deepest Cornwall.

Code:

03808 Camborne Observations at 00Z 02 Feb 2005
-----------------------------------------------------------------------------
   PRES   HGHT   TEMP   DWPT   RELH   MIXR   DRCT   SKNT   THTA   THTE   THTV
    hPa     m      C      C      %    g/kg    deg   knot     K      K      K 
-----------------------------------------------------------------------------
 1030.0     88    7.8    4.5     80   5.15     10     12  278.6  292.9  279.4
 1029.0     96    7.8    4.2     78   5.05      9     12  278.7  292.7  279.5
 1020.0    167    7.4    3.7     77   4.92      5     13  279.0  292.6  279.8
 1000.0    327    5.8    3.3     84   4.87    354     14  278.9  292.5  279.8
  993.0    384    5.3    3.2     86   4.87    350     15  279.0  292.5  279.8
  963.0    634    3.0    2.7     98   4.85     11     15  279.1  292.6  280.0
  950.0    744    2.3    2.0     98   4.69     20     15  279.6  292.6  280.3
  936.0    864    1.6    1.3     98   4.51     34     16  280.0  292.6  280.8
  925.0    959    2.8   -6.2     52   2.61     45     17  282.2  289.8  282.6
  917.0   1030    7.6  -12.4     23   1.62     49     19  287.8  292.8  288.1
  914.0   1057    8.2  -18.0     14   1.02     50     20  288.7  291.9  288.9
  905.0   1139   10.0  -35.0      3   0.22     48     21  291.3  292.1  291.4
  887.0   1305    9.0  -36.7      2   0.19     45     24  292.0  292.6  292.0
  853.0   1628    7.0  -40.0      2   0.14     31     22  293.2  293.7  293.2
  850.0   1657    6.8  -39.2      2   0.15     30     22  293.3  293.8  293.3
  820.0   1948    4.4  -38.8      3   0.16     20     20  293.7  294.3  293.8
  777.0   2385    0.8  -38.2      4   0.18     16     23  294.4  295.1  294.5
  772.0   2436    0.4  -38.3      4   0.18     15     23  294.6  295.2  294.6
  739.0   2784   -2.0  -38.7      4   0.18      0     25  295.6  296.3  295.6
  712.0   3079   -4.1  -39.1      5   0.18      3     24  296.5  297.1  296.5
  700.0   3213   -5.3  -29.3     13   0.49      5     23  296.6  298.2  296.7

Sure enough, 1.6 degC at 864m, 10.0 at 1139m.

Code:

03808 Camborne Observations at 12Z 02 Feb 2005

-----------------------------------------------------------------------------
   PRES   HGHT   TEMP   DWPT   RELH   MIXR   DRCT   SKNT   THTA   THTE   THTV
    hPa     m      C      C      %    g/kg    deg   knot     K      K      K 
-----------------------------------------------------------------------------
 1029.0     88    6.8    2.6     75   4.51    350     11  277.7  290.2  278.4
 1028.0     96    6.8    2.2     72   4.38    350     11  277.8  289.9  278.5
 1026.0    112    6.8    2.2     72   4.39    349     12  277.9  290.1  278.6
 1005.0    279    5.2    1.7     78   4.32    342     15  277.9  290.0  278.7
 1000.0    319    4.8    1.6     80   4.31    340     16  277.9  290.0  278.7
  984.0    449    3.5    1.2     85   4.25    335     19  277.9  289.8  278.6
  955.0    691    1.0    0.4     96   4.14    339     21  277.8  289.3  278.5
  944.0    784    0.4   -0.1     96   4.03    340     22  278.1  289.3  278.8
  925.0    947   -0.7   -1.1     97   3.83    340     23  278.6  289.4  279.2
  895.0   1210   -2.3   -2.8     96   3.49    331     26  279.6  289.5  280.2
  891.0   1247   -1.4   -4.2     81   3.16    330     26  280.9  289.9  281.4
  867.0   1467    4.2  -12.8     28   1.66    320     26  288.9  294.0  289.2
  854.0   1590    4.5  -14.0     25   1.52    315     26  290.5  295.2  290.7
  850.0   1628    4.6  -14.4     24   1.48    315     26  290.9  295.6  291.2
  836.0   1763    4.4  -18.6     17   1.06    318     28  292.1  295.5  292.3
  833.0   1792    5.4  -23.6     10   0.69    319     29  293.5  295.8  293.6
  824.0   1881    5.8  -23.2     10   0.72    321     30  294.8  297.2  294.9
  819.0   1931    5.4  -23.6     10   0.70    322     31  294.9  297.2  295.0
  786.0   2261    2.9  -24.8     11   0.65    330     36  295.7  297.9  295.8
  745.0   2690   -0.5  -26.4     12   0.60    335     34  296.6  298.6  296.7
  716.0   3009   -2.9  -27.6     13   0.56    335     38  297.3  299.2  297.4
  700.0   3190   -4.3  -28.3     13   0.53    335     40  297.7  299.5  297.8
  685.0   3360   -5.7  -29.7     13   0.48    339     41  298.0  299.6  298.1
  682.0   3394   -6.0  -29.9     13   0.47    340     41  298.0  299.7  298.1

and 12 hours later a similar inversion but at the sort of level you describe.