One thing that most runners or cyclists will notice at some point in their career is that there is always a headwind.
No matter which direction you are running or biking in, North, South, East or West, you can never avoid a headwind . You may be running or riding a circular loop, such as around a track or around the neighborhood, and notice that there is a headwind entire time. Why is that, you may wonder? There are a few reasons, really. It could be due to the weather, or it could be due to simple physics, or it could be due in large part to psychosomatic paranoia. Here are the most likely reasons that it may seem like there is always a headwind:
You really are running into a headwind.
The most obvious reason for there to seem like there is a headwind is because you are actually running into the wind. Just about any time that your direction of movement is directly opposite to the direction that the wind is moving, you are going to notice the headwind. In this case, you would not be imagining things. You really are running into a headwind.
The wind is blowing in any direction other than the one that you are running in.
The wind may not be blowing directly at you, but it may still feel like a headwind if it is coming from any direction other than behind you. It may be coming directly from your right side, or it may be coming from in front of you over to the left. You will notice that it will be buffeting you around, and just automatically assume that you are running into a headwind. It may even be coming from in front of you a bit, so that there is quite a range of physical directions that you could run in where it would seem like you have to fight the wind to move forward.
The wind may change directions as you run.
You may not be paranoid at all; the wind may in fact be changing directions so that you are actually running into a headwind the entire time. It may not happen as often as it seems to, but it is certainly a possibility.
All but the strongest tailwinds tend to go unnoticed.
Unless the wind is literally picking you up and propelling you forward (which can and does happen at times) you usually do not notice the presence of a tailwind. A headwind is something that you have to fight against; it is hard not to notice it. A tailwind may have no effect upon you at all, or it may just gently help you along unnoticed. If you are noticing the wind gusting from in front of you or to the sides for the majority of a run, then your mind may automatically discount the times that it was behind you because you did not remark upon it at the time and will instead just assume you had a headwind the entire time.
Air is heavy, and needs to be moved whether there is a wind or not.
The real reason that there is always a headwind is because, technically, there always is a headwind no matter which direction the wind is really traveling. This is because you are creating a headwind when you run. The air itself that is in front of you needs to be displaced by your body in order for you to occupy that space. Even if you are on an unventilated indoor track where the air is dead still, you create a small head wind in front of you the faster that you run. Even when there is a tailwind from the wind blowing in the same direction that you are running, you will still need to displace the air in front of you. The tailwind may more than make up for your effort spending to push the air in front of you out of the way, but you are still having to make that effort none the less.