Understanding Wind Barbs
The first time reading wind barbs can feel tricky. However, once you get the hang of it, you'll appreciate the amount of information they convey without the clutter of numbers. Wind barbs show direction and speed in a single symbol (sometimes called glyphs depending on your science background). Take these wind barbs below which show direction and speed.
Half barbs represent 5, whole barbs represent 10. Stacks of 10's and 5 can be summed to arrive at the general wind speed. Notice the "50" wind bard from the North. This closed triangle is the symbol (or penant) for 50. Hence the wind speed of 65 is (50 + 10 + 5) = 65.
Direction is based on "cardinal" direction, such as how a compass is referenced with North at the top and South at the bottom.
Wind barbs are rounded to the nearest 5. For example, the second wind barb above has one full barb and one half. This means that the wind speed is between 12.5 and 17.5. Depending on your units selected for wind speed, this is something to be aware of.
What about the units for speed!? We will show these barbs in the same units selected in your user profile. So if knots, or kilometers per hour is how you view wind, it will be reflected in these barbs as such.
When meteorlogists refer to wind, it is ALWAYS in terms of where the wind is coming from. In other words, when we say a "south flow" or a "south wind", for example, we mean that the wind is blowing out of the south. Or coming from the south. The point being, WIND BLOWS... it doesn't SUCK :) This simple adage can help you keep this straight.
Barbs are like arrows in a sense. Imagine an arrow with a feather end. When shot, it travels forward with the leading tip in front. These wind barbs can be considered "arrows" pointing downwind. When plotted in groups, such as on route or point forecast plots, or on maps, wind barbs show the area wind flow quite well in this same fashion. The tip of the wind barb points downwind and shows the larger wind field clearly. Do not confuse wind barbs as "vanes", such as on a windmill, which do point into the wind. Wind barbs are not those.
Take these two screen shots. One shows wind streamlines, the path the wind is traveling, while the other shows a field of wind barbs. Each represent the same winds over the same area. The scene is showing a small low pressure feature in the northern hemishpere, so winds are are rotating counter-clockwise around this region. Wind streamlines are handy to trace the trajectory of something inserted along a line, while wind barbs show the wind field in a uniformly spaced fashion.
Wind Barb Position
The visual default in XC Skies for wind barbs is to also plot the speed next to the tip. Wind barbs do take up space on a map or plot in order to show. Because they consume "space" we should point out that the tip of the wind barb is what the entire symbol represents. Let's take an exaggerated example to illustrate this. Let's say we want to plot a single wind barb on a map, like this:
So we have to ask, where is this wind barb applicable? Certainly not all of Central Europe! The answer is that the exact tip of the wind barb is the location the speed and direction represent. In this example it's in the middle of Poland.
In another example, consider that all of the below wind barbs represent the exact same location on this map in central Austria. The location of the wind barb tip is where the speed and direction should be referenced: