The diagram shows the weather minimums for Class B, C, D, E, and G. Class A is not listed because VFR flying is not permitted in that airspace. Now, let me explain how to read this diagram. Each box represents a different class airspace, which will have different weather minimums. Both visibility and cloud clearances will be depicted for each. Altitudes are depicted with red to help you understand that Class E and G minimums change with different altitudes. Now lets look at that weird blue squiggly. If you've guessed that the weird squiggly was meant to represent a cloud, you would be correct. The numbers next to the cloud represent how far you must remain horizontally from the clouds. The number above the cloud is how far above the clouds you must remain. Yes, you guessed it, the number below the cloud is how far beneath the clouds you must stay.
First we see Class B, which indicated that when you are within that airspace, you will need to remain clear of clouds and have a minimum of 3sm visibility. Moving along, we see that when we are in Class C or Class D, we will need a minimum of 3sm visibility and 2,000ft horizontally, 1,000ft above, as well as 500ft below the clouds. If you below 10,000 MSL and are in Class E or at night in Class G you will need the same with 3sm visibility and 2,000ft horizontally, 1,000ft above, 500ft below the clouds. If you're in Class E or G above 10,000ftMSL then you need a minimum of 5sm visibility and must remain 1sm horizontal, 1,000ft above, and 1,000ft below the clouds. If you are in Class G during the day and are below 1,200ft AGL then all you need is 1sm visibility and you need to remain clear of clouds. Now, if you are in Class G during the day below 10,000 MSL, but above 1,200AGL then you must have at least 1sm visibility, remain 2,000ft horizontal, 1,000ft above, and 500ft below the clouds.
Takeoff Minimums
Controlled Airspace: 3sm visibility and 1,000ft ceilings
Uncontrolled Airspace: 1sm visibility and clear of clouds
Lets Discuss
You may be thinking the same think I did the first time I saw all those numbers. "How on Earth am I supposed to remember all that?" My head was spinning. I found that understanding the rationale behind all those numbers helped me remember all the wether minimums much easier. VFR flying is based on the principle of "see and avoid". Meaning that it is the responsibility of the pilot to look outside and avoid other traffic.
It is presumed that aircrafts flying at lower altitudes (below 10,000 MSL) and/or radar approach control (or operating control tower) will be moving at a slower speed. Therefore, the slower aircraft won't need as much flight visibility or cloud clearances to "see and avoid" other traffic. This is opposed to the aircrafts flying at higher altitudes, which are presumed to not only be flying at faster speeds, but also on instrument flight plans. With faster moving planes, you will need more visibility and more distances away from clouds in order to "see and avoid" other planes zipping in and out of clouds.