Why is it sometimes not practical to use scale models when representing objects in space?

Iknow the answer to 13 is b and 14 is d. i just need to know why the correct answers are correct

After cloud droplets form, what must happen to them for precipitation to occur?

Read these sentences from the text. near the equator, the tropics receive the most rain on a consistent basis. as a result, the fresh water falling into the ocean decrease the salinity of the surface water in that region. [. .] . . as the salt content of sea water increases, so does its density. what can you infer about how rain affects the density of surface water near the equator?