Answer:
How do the Northern and Southern hemispheres differ in climate and temperature year-round?
The biggest factor in differences in the climate in the Northern and Southern Hemispheres has to do with the distribution of land vs. ocean. The Northern Hemisphere has much more of Earth’s land masses, while the Southern Hemisphere has a larger fraction of ocean.
There is more than one reason this is important. First, land and ocean heat and cool at different rates. Land heats up and cools down much faster (over a period of a day) compared with ocean (over a period of months).
Second, there mountains on land that act as physical barriers to wind flow. Air responds to these barriers in different ways, both from creating local changes upwind and downwind of mountains (wetter in the case of the former, drier in the case of the latter), to having continental effects (the Rocky Mountains create atmospheric waves thousands of kilometers in size that affect the continental US all the way to the east coast and North Atlantic).
Meanwhile, in the southern hemisphere, the Antarctic Circumpolar Current flows unobstructed around the continent of Antarctica. With no land to divert winds, the atmospheric circulation around Antarctica is stronger than at the same latitude in the Northern Hemisphere
