Notes: Surface The following two links explain the symbols on the surface map:

Surface Station Model Explained

...and another explanation

Vasquez also has an explanation of the surface station model in an Appendix.

Note that at automated stations, the clouds may not be observed if they are higher than some level, and the current observed weather may not be reported.

The following table shows the common symbols used for the current observed weather at a station:

Snow intensity is associated with visibility. In the absence of other obstructions to vision (such as fog, haze, blowing snow, etc):

Heavy snow: visibility 1/4 mile or less
Moderate snow: visibility 1/2 mile or less, >1/4 mile
Heavy snow: visibility greater than 1/2 mile

So during a snow event, it is useful to look at the visibilities reported from the weather stations -- even when the station is not reporting the current observed weather, the visibility is a useful clue.

Here's a chart of cloud types:

Cloud types are not typically reported any longer. Note that stratus, stratocumulous, and cumulus are below 6,000 ft, which is below about 1800 meters. This is typically between about 850mb and 800mb. Mid level clouds such as altostratus and altocumulus are between 6,000 and 20,000 ft., which is between 1800m and 6100m. So these clouds are found at the 700mb to 500mb levels. Cirrus type clouds are found above this, at the 300mb and 200mb levels.

Cumulonimbus

Halos

Electromagnetic radiation has a big impact on surface weather. Here's an intro to radiation in the atmosphere:

Radiation Lecture