Final answer:
Trees attract lightning due to their height, making it dangerous to shelter under them during thunderstorms. Metal objects like golf clubs can also attract lightning, increasing the risk. Cars offer safety as a Faraday cage, keeping the electrical charge on the exterior.
Step-by-step explanation:
The reason one should not stand under a tree during a thunderstorm is that trees can attract lightning due to their height. Lightning tends to strike the tallest objects in an area, and since trees are often the tallest points, especially in an otherwise open space, they are more likely to be struck. This makes it dangerous to take shelter under a tree during a thunderstorm because if the tree is hit, the lightning can potentially jump to or pass through a person standing nearby, causing serious injury or even death.
A golfer with a metal club over her shoulder is particularly vulnerable in an open fairway because the metal club acts as a conductor for electricity, increasing the risk of attracting a lightning strike. Standing under a tree is not safer because the tree could be hit by lightning and pose a risk to anyone underneath. A tree might seem like shelter, but it actually increases the danger.
As for vehicles, the metal body of a car acts as a Faraday cage during a lightning strike or when a downed line touches the car, keeping the electrical field on the outside. This means the inside of the car remains unaffected, provided the occupants do not touch any metal parts of the car's frame. Thus, staying inside a car during a thunderstorm can provide a measure of safety.