A) Get the cheapest kestrel, and live with it around your neck for a month or two. Correlate what you see and feel around you with an actual wind speed.
B) Get a spotting scope. Spend time in open fields where the wind you feel (wind at your position) is the same as the wind you see in the scope. Correlate the mirage you see, with an actual wind speed on the kestrel.
Do this for a few months, and you will be way ahead of the game.
https://www.amazon.com/Kestrel-Pock...XR5GWCRZ8WY&psc=1&refRID=8C18191SWXR5GWCRZ8WY
Most mirage representations you find in those charts are way too course. There are distinct clues that can help you call what you are seeing and feeling to within 1mph up until you get to 8mph of wind.
0 mph - very rarely exists
1 mph - is more of a wind "impression" than a breeze. Open your freezer and stick your head so you can feel the cold air falling out. That is about what 1 mph feels like. In the spotting scope, the mirage still looks like a boil.
2 mph - The hairs on your arm will start to tickle, you can feel direction on your face. Tops of grasses begin to twitch; small leaves of deciduous trees begin to inconsistently twitch. Mirage just begins to get some organization and direction. Just slightly off vertical.
3 mph - Hairs on your arm move consistently, light grasses move furtively, leaves of deciduous trees continuously twitch around. Mirage is about 30 degrees off vertical.
4 mph - If you turn your face into the wind, you can just begin to hear the wind rattle in your ears. Deciduous leaves stay busy and the twigs they are attached to begin to sway. Grasses are in constant motion. Mirage is 45 degrees off vertical.
5 mph - The wind is a constant rattle in your ears, your loose clothing is just beginning to be pressed against your body. The smallest limbs of deciduous trees begin to move furtively. Grass begins to lie over. Mirage is about 50 degrees of vertical.
6 mph - Loose clothing is constantly pressed to the body, small limbs of deciduous trees in constant motion. Mirage is about 60 degrees off vertical.
8 mph - Main limbs sway. Mirage is about 70 degrees off vertical.