Provide the sunrise time recorded by the home weather station of store no.30 on 2014/2/21.
store no. 30 refers to store_nbr = 30; on 2014/2/21 refers to date = '2014-02-21'
SELECT T1.sunrise FROM weather AS T1 INNER JOIN relation AS T2 ON T1.station_nbr = T2.station_nbr WHERE T1.`date` = '2014-02-21' AND store_nbr = 30