Amman is 773 M (2,356 FT) above sealevel. When you head west down, literally, the highway, the elevation begins to drop dramatically. The drive takes you along a ridgeline and then into the Jordan River valley. Our destination this afternoon was Amman Beach, 420M (1,378 FT) below sealevel. Bonus: Since it's the middle of the week, it was empty!
The Dead Sea is more like one of America's Great Lakes... there's just nothing alive in it, and, due to the incredibly high saline & mineral content, anything thrown in it floats. Everything is more harsh in the valley. When we left Amman, it was 21 (69). By the time we reached the beach parking, it was 34 (93). The Dead Sea receives an annual rainfall of about 2 inches a year. Due to the high demand for water from the Jordan River, the Sea has been dropped consistantly, losing one meter of surface area annually for the past few years.