The atmosphere is divided into layers from lower to higher they are: the troposphere, stratosphere, mesosphere, thermosphere, and exosphere. But the troposphere is special for Containing almost all of the total atmospheres water vapor, therefore the vast majority of cloud formation process such as convection occurs in the troposphere.
In addition to this, for being the lower layer the earth surface is in constant interaction with the troposphere, Clouds and winds form in this layer and the temperature is conditioned by factors such as humidity and thickness of the layer (16 to 18 km in the Equator) making the troposphere the most responsible for the weather.
The NAFTA is going to increase the pollution. This will lower the U.S. environmental standards. This will also cause a huge amount of pollution in Mexico.
