In our final “Tricks of the Trade” installment at Rodeo Houston, we chat with two rodeo clowns. They may dress and act funny, but they take their jobs seriously. Also known as barrelmen, rodeo clowns protect bull riders when they fall. Plus, air travel worldwide continues to be affected by the closure of London’s Heathrow Airport. And, copper — it’s not just for drinking mint cocktails. Yet a copper economic indicator is now muddled.