The title of this exercise is labeled as the Physical Planet but I don't think that is the real aim here. The real goal is to develop ten ways in which the weather can be utilized as a character or plot device to drive the story forward. I have used this to great effect in the past, but one must be careful to not remove player agency here. Set up the scenario and let the players come up with their own solutions.
The Exercise
What role do you anticipate weather playing in your story? Do you have a lot of travel that you want to complicate with bad storms? Are you going to snow in your mighty heroes? Will there be a mighty battle, determined by sudden flooding? You actually don't need to know right now. Your exerise for today is to jot down ten plot devices that relate to weather, and what you think they do to the story (for example: a snow-in can turn the mood very claustrophobic... or very intimate).
1) A Fey Crossing allows a magical storm to blanket the area. The source of the storm could be a magical object, magical creature or the Frost Queen herself. Players can seek the source of the winter storm to end the blight, seek shelter and find other dangers doing the same, or be driven to a villains home.
2) Unseasonably warm temperatures have brought about a drought. Food and water are scarce. Raiders attack villages seeking resources. Wells are drying up. Martial law is declared. Water merchants inflate prices. Magical cooling and water creation become powerful spells. Guards can be bribed for water shares.
3) A caravan needs guarding but when the PCs hire on to the job they are stuck in the pass due to an avalanche, mudslide etc. The party must survive and fend off the monsters not effected by the weather.
4) A tsunami uncovers a long lost dungeon on a nearby island. Two nations claim ownership. Will the party unearth long lost magic for themselves or one of the nations?
5) Sky worshipping giants gather nearby. The tribes' shaman fore tells a lightning storm as a signal for war.
6) Rumors tell of a ghost ship with frayed sails and crewed by the undead sighted during squalls off the coast. When a princess disappears, can the party survive the weather?
7) A flood washes out the main bridge on a prominent trade route. The owners of the bridge refuse to rebuild and perishable goods need to be delivered to the lands beyond.
8) A small village is unaffected by the severe weather in the area. Refugees from a neighboring village seek shelter but an old feud prevents the refugees from being allowed in. Who sill the PCs side with?
9) Several weeks of rain have left travel a difficult prospect. The party can risk it losing equipment and time slogging along the road or hole up in a village/town etc. The village is plagued by witches, vampires, demons etc. Will the party face down the trouble or brave the roads?
10) An earthquake frees a trapped evil. Milk spoils, crops wither, and livestock dies. The local populace begs the PCs for aid.
Some useful tools
Spreadsheet Customizable Weather
