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.

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.

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.