Actually a wide brimmed had (such as a cowboy hat) is practical. As Metchosin stated it keeps the rain well of you and harmful sun rays off your neck. That's why the Ontario Provincial Police were issued those Mountie or Smokey hats. Reason being (from what I heard) is that an OPP officer developed skin cancer on his neck. He subsequently sued on the basis that the force did not issue appropriate head gear.

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