K-index (meteorology)

The index is derived arithmetically by:^[3]

${\displaystyle K=(T_{850}-T_{500})+T_{d_{850}}-(T_{700}-T_{d_{700}})}$

Where :

${\displaystyle T_{d_{850}}}$ = Dew point at 850 hPa

${\displaystyle T_{850}}$ = Temperature at 850 hPa

${\displaystyle T_{d_{700}}}$ = Dew point at 700 hPa

${\displaystyle T_{700}}$ = Temperature at 700 hPa

${\displaystyle T_{500}}$ = Temperature at 500 hPa

The K Index is related to the probability of occurrence of a thunderstorm. It was developed with the idea that Potential = 4 x (KI - 15), which gives the following interpretation:^[1][4]