What are lines joining places of equal pressure on the sypnotic weather map called

Characteristics of substance farming include all of the following except

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

17. the soil erosion pictured here is the result of what? a. harvesting renewable resources at a rate greater than the sustainable yield b. a mudslide caused by excessive rains c. harvesting renewable resources at a rate lower than the sustainable yield d. the transition between geologic eras and eons