“Just remember, every cloud has a silver lining. Except for mushroom clouds. They have a lining of Iridium and Strontium-90.” This is just one of many witticisms that the new Carrot Weather for Mac ($10) will entertain you with as you try to figure out whether to bring an umbrella with you for the day. Billed as an app “overflowing with personality,” Carrot’s weather forecasts are anything but dull, with dialogue, characters, and scenery that will change in surprising and unexpected ways.