Countdown to Endeavour: Rockets Can Trigger Lightning Strikes

Kathy Winters is an Air Force Civilian Meteorologist at the 45th Weather Squadron at Cape Canaveral Air Force Station. She is the Space Shuttle Launch Weather Officer providing weather support to the Space Shuttle Program at Kennedy Space Center as the Launch Team prepares for the 29 April 2011 launch of Endeavour. You can find out more about the 45th Space Wing at their Facebook page.

Cumulus Clouds Near Vehicle Assembly Building

Cumulus Clouds Near Vehicle Assembly Building (Photo by Kathy Winters)

I took a picture of this cumulus cloud from the press site on Tuesday morning after the countdown status briefing. Clouds like this formed along the sea breeze due to our moist atmosphere. Although these clouds are normally harmless, on launch day the 45th Weather Squadron Launch Weather Team actually pays close attention to the height of any cumulus clouds like these that develop within 10 nautical miles of the launch pad. If a cumulus cloud gets tall enough, it may violate our cumulus cloud rule, one of the many rules in our Launch Commit Criteria (PDF). The purpose of the cumulus cloud rule is to prevent the threat of triggering a lightning strike when launching into elevated electric fields in the atmosphere. Fortunately, we do not expect significant cumulus clouds to be in the area this Friday.

Did you know a rocket can trigger a lightning strike when there is no natural lightning occurring? The Lightning Launch Commit Criteria protect the Shuttle and other rockets from the threat of triggered lightning. See how scientists at the University of Florida study triggered lightning by launching rockets into elevated electrical fields.

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