1. When cities in the Northern Hemisphere are having their coldest temperatures, what is happening in the Southern Hemisphere?
2. The two cities near the equator have nearly the same temperature all year. Is that true for other places?
3. What is the variation in temperature over the course of a year called?

1. The Southern Hemisphere would be having it’s hottest temperatures.

2. Depends, if you are near each other yes, but say Antarctica and Florida won’t have the same temperatures as each other because they are different climates.

3. diurnal temperature variation.

Explanation for 1:

The two hemispheres are opposite, one is hot, one is cold. Therefore, the Southern Hemisphere would be having it’s hottest!

c. earths continental crust is thicker than its lithosphere.

because, the lithosphere is the outermost layer of the earth/ 100 km thick and is defined by its machanical properties.the lithosphere contains oceanic and continental crust that varies in age and thickness across locations and geologic time. the lithosphere is the coolest layer of the earth in terms of temperature. the term lithosphere should not be confused with the use of "geosphere" which is used to indicate all of earth systems, including the atmosphere, hydrosphere   and biosphere. the surface of the earth can be divided into the continental crust and the oceanic crust.   the continental crust is made mostly of granite while the oceanic crust is made of basalt. the average thickness of the continental crust is 25 miles and the average thickness of the oceanic crust is 5 miles.   three types of rock, igneous, sedimentary, and metamorphic, make up the surface of the earth. that's why 3 option is preferable.