Tropic of cancer who did invent and which year? ​

What is the correct order of events in the water cycle?

Given: circle a externally tangent to circle b. how many possible common tangents to circles a and b can exist? 2 3 4

Dubai is challenged by all of the following environmental factors except a. a warm and dry climate b. a lack of annual rainfall c. scarce freshwater resources d. a lack of valuable natural resources