Variable Gases + Atmospheric Pressure and Structure (Video)

Another atmospheric gas with 2 roles is Water Vapor Water vapor is invisible – don’t confuse it with cloud droplets Atmospheric amounts vary between almost 0% in deserts to 4% in tropics Typical values in our area are about 1-2% Some satellites sensors can detect actual water vapor in atmosphere Water Vapor Image Visible Image 2

Aside from providing us with precipitation, H2O Vapor….. ….stores a ton of heat!

Another gas which stores a ton of heat is Carbon Dioxide (CO2) Small percentage of total atmosphere But, very important green house gas Sick of hearing about CO2?? How many have seen the movie “An Inconvenient Truth” or read the book? Mauna Loa Observatory 4

Aerosols are an important part of our atmosphere Tiny, solid airborne particles Aerosols can be man-made (smoke, ash) or naturally occurring (like sea salt or dust) AKA Cloud Condensation Nuclei Some aerosols are very beneficial and, in fact, are required for condensation to occur. Video 1 Video 2 5

Atmospheric pressure is the weight of all the air molecules in a column of air above the surface • So, Atmospheric pressure is simply the weight of the air. As you ascend (go up), atmospheric pressure decreases Why?

Because Air Density Decreases

Atmospheric pressure increases increases less decreases If more air molecules are packed into a column, the density ___________ and the atmospheric pressure __________. On the other hand, when there are fewer molecules in the column, the air weighs _______and the surface pressure __________. increases increases less decreases

Average sea-level pressure = 1013.25 mb or 29.92 in. Most common units for atmospheric pressure are millibar (mb) and inches of mercury Average sea-level pressure = 1013.25 mb or 29.92 in. So, the numbers you see on Weather Maps should start meaning something to you right about now ---------------> 9

Air pressure is Measured using a barometer…. Video

The vertical structure of the earth’s atmosphere is complex The atmosphere is composed of different layers

A View from Space. How deep is the atmosphere?

Draw this!

Troposphere- lowest level All Weather occurs in this region Temperature decreases with height This is because sunlight warms the surface of the earth, which then warms the air above it. The rate at which air temperature decreases with height is called the lapse rate. Average lapse rate = 6.5°C/1000m = 3.6°F/1000 ft

Stratosphere Ozone Layer is located here Ozone Video Temperature increases with height Usually, the higher up you go, the cooler it gets So, when it gets warmer as you ascend, we call it an inversion This happens in the lower atmosphere (troposphere) too In fact, the area of the world where it happens most is right here on the Central Coast of California We will talk more about this later….

Mesosphere The prefix, Meso = middle, so the mesosphere is the middle layer of the atmosphere Temperature decreases with height

Video Thermosphere Contains the ionosphere, where Auroras occur Temperatures increase with height Video