One of my friends is stuck in Houston at the moment - she was supposed to fly back to the UK today, but her flight was delayed 4 hours (due to a technical problem), then their plane took off, got to Canada, then had to turn around and go back to Houston again! The ironic thing is though that the whole reason she was travelling today was because she takes measurements from volcanic ash clouds for her PhD research and was on her way back from collecting data from volcanic plumes in Nicaragua!