Answer:
Greenhouse effect
Explanation:
Greenhouse effect is the trapping of the sun's warmth in a planet's lower atmosphere, due to the greater transparency of the atmosphere to visible radiation from the sun than to infrared radiation emitted from the planet's surface.
The earth tilts for different times of the year. During the summer Alaska is a lot closer to the sun than florida.
The disease has infected a few people, spread out over a large distance because Cholera can't suddenly spread, it infects few people and then spreads rapidly.
I will say distance from the sea, ocean currents, direction of prevailing winds
