Notes:

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The first part of this presentation focuses on basic atmospheric science. We can divide the atmosphere into four sections: the troposphere, the stratosphere, the mesosphere, and the thermosphere. For all practical purposes, we are concerned only with the troposphere in air quality modeling, since the troposphere is that part of the atmosphere that we interact with the most. The troposphere has a height of roughly 11 km (or a little more than 6 miles), and, when combined with the stratosphere, contains 99% of the Earth’s atmosphere. Between the troposphere and the stratosphere is the “tropopause”, a dividing line if you will between the two lower atmospheric spheres. The height of the tropopause is variable, and is determined by several techniques, mostly through readings (called “soundings”) taken by balloons released from many locations twice a day.

While we are not unconcerned with air quality in the stratosphere (as you will see on the next slide), for purposes of this particular air quality model (AQM), we focus our attention in this model on the troposphere.