A-- Initiative. Referendums have to do with only addressing a single, specific issue. Federalist systems have to do with having a representative head to the government. Supremacy clauses have to do with which laws are superior to others in case of conflict. (Federal law is superior, by the way.)
A low pressure system has lower pressure at its center than the areas around it. Winds blow towards the low pressure, and the air rises in the atmosphere where they meet. As the air rises, the water vapor within it condenses, forming clouds and often precipitation.
The sinking of the Lusitania in 1915 enraged american opinion of the German Empire. This sowed the seed with the then Secretary of State William Jennings Bryan, a pacifist, resigning. FYI the Lusitania was a British ocean liner that ferried american and Europeans across the Atlantic.