1) The word "umbrella" contains three vowels: U, E, and A.

2) The coldest known temperature in the universe was achieved in a laboratory in 2019, reaching a fraction of a degree above absolute zero (-273.15 degrees Celsius).

3) The word "mountain" contains three vowels: O, U, and A.

4) The world's largest desert is the Sahara Desert in Africa, covering an area of about 3.6 million square miles (9.4 million square kilometers).