Database: sales_in_weather
Question: Tell the wet-bulb temperature of the weather station which contained store no.6 on 2012/2/15.
SQL: SELECT T1.wetbulb FROM weather AS T1 INNER JOIN relation AS T2 ON T1.station_nbr = T2.station_nbr WHERE T2.store_nbr = 14 AND T1.`date` = '2012-02-15'