It Becomes Dense. Warm air pushes cold air down, creating an inversion.

Rabbit. In Australia, rabbits are considered a serious pest that is responsible for widespread erosion.

Stratosphere. The stratosphere is the second layer of the Earth's atmosphere.

1.5 Volts. The D sized battery can supply power for a longer time than C, AA or AAA cells at equal current levels.

186. The North Pole has six months of uninterrupted darkness every year.

Desalination. Six gallons of desalinated sea water renders about 1.75 pounds of salt.