A windsock points the way the wind is going, and airplanes take off and land into the wind, opposite the direction the sock streams. A segmented circle around the sock can show that a runway uses right traffic. A spoken wind, such as an ATIS report of 210 at 10, is named for the direction the wind comes from.
The rule
The sock streams downwind. Fully extended and pointing east, it is being blown toward the east, which means the wind is from the west. Manned aircraft then take off and land toward the west. They do not take off in the direction the sock points. The wind does determine which runway is in use. "Either direction" is not the reading.
A segmented circle is the airport's traffic-pattern indicator, usually with the wind cone in the middle and L-shaped markers showing the direction of turns. When a marker shows right traffic for a runway, that runway's pattern is right-hand even though the standard pattern is left. Take the sock and the marker as a pair. A sock streaming north indicates wind from the south. Runway 18 points generally south, into that wind, so Runway 18 is the favored end. If the segmented circle shows a right-traffic indicator for Runway 18, the pattern for that runway is right-hand. The wind is not from the north in that picture, and it does not favor Runway 36. The pattern is not a standard left pattern for Runway 18 when the indicator says right.
Spoken wind uses the same from-direction. "Wind 210 at 10" means the wind is blowing from 210 degrees at 10 knots. 210 degrees is about south-southwest, so the air is moving from the south-southwest toward the north-northeast. It is not coming from due north, and it is not blowing toward 210. The runway numbers page is where 18 becomes about 180 degrees and 36 becomes about 360. The leg order for whichever pattern the circle indicates is on airport traffic pattern.
How to apply it
Look at the sock before you launch near a non-towered airport, as part of the weather and airport picture in §107.49. Point your finger along the sock, from the mast toward the tip. That is downwind. Turn around. That is the direction airplanes will face on the runway in use. Then read the segmented circle. If the marker for that runway end is a right-hand pattern, expect the downwind leg on the right side of the landing direction. Your small unmanned aircraft still must not interfere with that pattern under §107.43. Where to put the aircraft once you know the pattern is on operating near airports.
If you also have an ATIS or a weather broadcast, trust the from-direction in the numbers and use the sock as the picture on the field. A report of 210 at 10 and a sock streaming toward the northeast are the same story: wind from the southwest side of the rose, airplanes pointed into it. Do not invent a radio call from the sock. Use it to predict the runway and the side of the pattern.
Eastbound sock, south wind, and a 210 report
Before launch, the sock is fully extended and pointing east. Expect takeoffs and landings toward the west. An airplane pointed east, the way the fabric points, would be departing or landing downwind. That is the wrong expectation.
At the next field the sock streams north and the segmented circle carries a right-traffic indicator for Runway 18. The wind is from the south. Runway 18 is favored because it points south, into the wind. Arrivals and departures on that runway use a right-hand pattern. Drawing a left pattern, or favoring Runway 36, misreads both the sock and the marker.
The ATIS on the drive in said "wind 210 at 10." That wind comes from the south-southwest and goes toward the north-northeast. It does not come from due north, and 210 is not the direction it is blowing toward. Match that report to the sock before you decide which final approach to stay away from.
The trap
The eastbound-sock item says airplanes take off toward the east, the way the sock points, or that wind does not determine the runway. The sock points downwind. Aircraft take off and land into the wind, toward the west in that example.
The segmented-circle item says the wind is from the north and favors Runway 36 with a standard left pattern, or that the wind is from the south but favors Runway 36 with every pattern left-hand. A sock streaming north is wind from the south. Runway 18 is the into-wind end. The indicator specifies right traffic for Runway 18.
The ATIS item says the wind is coming from due north, or blowing toward 210. Wind is named for the direction it comes from. 210 at 10 is from the south-southwest toward the north-northeast.
Read a few socks on the free practice test. The course puts the sock, the segmented circle, and the spoken wind in one airport lesson so the runway in use is predictable.