Earth can be considered a sphere; the tropics are the imaginary lines that are drawn to divide the earth. The Earth has barely a 0.33 percent of leveling at the poles.
And let us finish with the influence of the 23,5 of inclination of the axis of rotation in the solstices of summer and of winter.
On the first of them (summer), the Sun impact perpendicular over the parallel that is located 23.5″ over the Equator, that is called Tropic of Cancer.
And let us follow with the famous 23.5º. If from the North Pole we move towards the South those 23.5º we will reach that is called the Arctic Polar Circle (that is why is said that its latitude is 66.5º North, that is the difference from 90ª to 23.5º).
Between this parallel and the North Pole, the Sun will not put all the time that the Earth takes in a complete rotation the day of the summer solstice.
It is the famous sun of midnight. The same can reason on the South Hemisphere and we will reach the tropic of Capricorn and to the Antarctic Polar Circle.
And between this and the South Pole, it will have complete darkness as long as the Earth goes a complete rotation that day. But six months later the roles of hemispheres will reverse and the Sun will place perpendicular over the tropic of Capricorn.
Equatorial climates are characterized with some abundant rains (between 1500 and 2000 liters to the year and even more) and are spread almost equally for all the months of the year.
Temperatures are always hot, over 20°C in average all the days and all the months.
The thermal range annual is lower than 5º and even occasionally of just 1º. This climate is located in the equatorial belt of the Earth.
The tropical climate is characterized with some hot temperatures over 20°C all the months of the year.
The rains are abundant although less than the equatorial climate and are characterized by the existence of a season of rain that can last between 3 and 9 months to the year and a season of drought that can last between 3 and 9 months to the year.