The Navajo are the second largest tribe in the U.S. and they have the largest reservation stretching across Colorado, Utah, New Mexico and Arizona with over 25,000 square miles. They were also among the largest group of Indians to migrate to Los Angeles in the 1950s and 60s.
The ionosphere is a shell of electrons and electrically charged atoms and molecules that surrounds the Earth, stretching from a height of about 50 km (31 mi) to more than 1,000 km (620 mi).
Letâs examine each of these four spheres in detailâ¦â¦â¦. The Atmosphere The Earth is surrounded by a blanket of air, which we call the atmosphere. The atmosphere consists of five unique layers (the troposphere, the stratosphere, the mesosphere, the thermosphere and the exosphere).