altitude usually refers to a height in the air (above sealevel) and elevation refers to height on the surface [of the Earth] above (or below) sealevel.
Mojave Dictionary, Los Angeles: UCLA, 1992, 77頁 Lynch, David K. Land BelowSeaLevel. Geology.com. [2010-04-26]. (原始内容存档于2014-03-27). Mojave Des. - 莫哈維沙漠