Most of climate is dictated by the way that heating is distributed. It also depends on the tilt of the Earth's axis which gives us the seasons, and by the distribution of oceans, which store the Sun's heat and moderate the climate. Regions far from the ocean experience greater extremes of hot and cold weather, and may also be drier.
The warm tropical regions are traditionally the ones between latitudes 23.5° north and south, lines of latitude known as the "tropic of cancer" and the "tropic of capricorn." Anywhere in that region, which straddles the equator, at least one day exists in the year when the noontime Sun is directly overhead. And the polar regions are the regions poleward of the arctic circles (latitude 66.5°) where at least on one day in winter, the center of the Sun is below the horizon all day long. Those are the regions experiencing "polar night" in midwinter, and hardly any plants survive there. In mid-summer, polar days get very long, but with the Sun close to the horizon, its rays arrive at a shallow angle and their heating power is minimal.
The Sun's energy input is what drives climate, but the atmosphere also has an important role. Heat given to the ground does not stay where it is deposited. Sooner or later the warm ground radiates it away in the form of infra-red light. Those infra-red rays, in turn, do not travel far before being re-absorbed by greenhouse gases such as water vapor (see S-1 Sunlight and the Earth). Later those gas molecules again give up their heat, also as infra-red radiation, some of which reaches further upwards. By such a chain of absorption and re-emission heat gradually spreads, like sunlight in a fog, until some of it reaches rarefied levels from where it can be radiated to space, never to return.