PLT OF JUMP PLANE DOES NOT HALT RELEASE OF JUMPERS ABOVE CLOUD LAYER.

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I WAS FLYING AN SMT FOR SKYDIVING ACTIVITIES AT DELAND ARPT. I HAD FLOWN 2 LOADS AND NOTICED THAT THE CLOUDS WERE CLOSING IN AND THAT SEVERAL LAYERS WERE FORMING. WE HAD BEEN ABLE TO SPOT THE ACFT OVER THE DROP ZONE WITHOUT ANY DIFFICULTY; HOWEVER; BECAUSE OF NUMEROUS BREAKS IN THE CLOUDS. ON THE THIRD LOAD; AS WE WERE CLBING TO ALT (13;500 MSL) THE HIGHER LAYER (APPROX 10000 MSL) MOVED OVER THE LOWER ONE OBSCURING MY VIEW OF THE DROP ZONE. I KNEW WE WERE OVER THE ARPT; USING THE LORAN; AND INTENDED TO WAIT UNTIL THE CLOUDS PASSED BEFORE DROPPING THE JUMPERS. THE JUMP MASTER IN THE BACK OF THE PLANE CALLED FOR THE 'LIGHTS ON'; WHICH ENABLED HIM TO GIVE L OR R CORRECTIONS ON HDG. I INFORMED HIM THAT I DID NOT HAVE THE DROP ZONE IN SIGHT YET. HE INFORMED ME THAT HE DID AND GAVE A SMALL CORRECTION ON HDG. NORMALLY I WOULD NOT LET JUMPERS EXIT IN THIS WX CONDITION BUT THEY OPENED THE DOOR IN THE REAR AND EXITED. I IMMEDIATELY TURNED OFF THE 'LIGHTS' AND DSNDED BELOW THE CLOUD LAYERS IN VFR CONDITIONS HOLDING THE REMAINING JUMPERS ON BOARD. SEVERAL EXITED ON ANOTHER PASS OVER THE ARPT AT 3000 WITHOUT INCIDENT. OTHERS RODE DOWN WITH THE AIRPLANE AND LANDED. I MADE NO MORE FLTS THAT DAY. IT IS ILLEGAL TO DROP PARACHUTES THROUGH THE CLOUDS AND IT WAS NOT MY INTENT; HOWEVER; I DID NOT EMPLOY ENOUGH COMMAND BY TERMINATING THE JUMP RUN BEFORE THEY EXITED. I SHOULD HAVE BEEN ABLE TO TELL THAT THE CHANCES OF SUCCESSFUL VFR SPOT WERE QUICKLY DETERIORATING. I LEARNED THAT SKYDIVERS OFTEN DO NOT THINK OF THE LEGALITY OF ALL OF THEIR ACTIONS AND THAT I COULD QUITE POSSIBLY WIND UP BEING VIOLATED FOR NOT STOPPING SOMETHING THAT THEY DO; SINCE I AM PIC AND RESPONSIBLE FOR THEIR SAFETY.