Water normally boils at 100 degrees Celsius (212 degrees Fahrenheit). But for each 500-foot increase in altitude, the boiling point drops about one degree. Water therefore boils much more quickly in Denver, Colorado, than it does in Honolulu, Hawaii. But, because the actual temperature of the water does not increase, it takes longer to cook food.
elevation, or the physical distance above the ground.
to change or modify something to fit with something else.
vehicle able to travel and operate above the ground.
force pressed on an object by air or atmosphere.
device for measuring altitude.
the distance above sea level.
illness caused by reduced oxygen levels at high elevations.
slanting space between two lines that ultimately meet in a point.
to go up.
the study of space beyond Earth's atmosphere.
layers of gases surrounding a planet or other celestial body.
an invisible line around which an object spins.
flow of blood through an organism's body.
natural or artificial line separating two pieces of land.
determining an object's position using the stars and planets as guides.
large settlement with a high population density.
all weather conditions for a given location over a period of time.
result or outcome of an action or situation.
number of things of one kind in a given area.
height above or below sea level.
to force or pressure.
to grow or get larger.
state of matter with no fixed shape that will fill any container uniformly. Gas molecules are in constant, random motion.
slowly, or at a measured pace.
physical force by which objects attract, or pull toward, each other.
line where the Earth and the sky seem to meet.
amount of water vapor in the air.
to display or show.
person who studies patterns and changes in Earth's atmosphere.
smallest physical unit of a substance, consisting of two or more atoms linked together.
someone who climbs mountains.
series or chain of mountains that are close together.
half of the Earth between the North Pole and the Equator.
the star Polaris, located roughly above the North Pole. Also called the Lodestar or Pole Star.
chemical element with the symbol O, whose gas form is 21% of the Earth's atmosphere.
star that is currently located roughly over the North Pole. Also called the North Star or Lodestar.
extreme north or south point of the Earth's axis.
any area on Earth with one or more common characteristics. Regions are the basic units of geography.
base level for measuring elevations. Sea level is determined by measurements taken over a 19-year cycle.
large ball of gas and plasma that radiates energy through nuclear fusion, such as the sun.
to reach the highest point of a mountain.
sign or indication of something.
developed, densely populated area where most inhabitants have nonagricultural jobs.
up-down direction, or at a right angle to Earth and the horizon.