Why is the wind always blowing the wrong way on the MVT?

[EasyRider]

You know, in my face, and at the back of the rider going the opposite direction?

I recently moved and am using the MVT instead of the Custis Trail. It's a better commute but I am still getting used to the breeze. Would any of you MVT regulars care to describe what you've learned about the habits of the Adversary on the MVT? Which direction he usually travels and why, his seasonal patterns, and how to best him?

[MCL1981]

The wind is most commonly out of the southish. Meaning it will be at your back in the morning and in your face on the way home. Second most common appears to be the opposite, out of the northish. It will vary out of the westish when it is shifting between north and south. Out of the eastish is least common.

This is a scatter plot from the DCA ASOS for the year 2011. It may take a bit to load. It is a LOT of data. You can see that in the winter, it is kinda all over the place, mostly south-west-north. In the spring through fall, it tends to favor out of the south.
http://www.wunderground.com/history/...q_statename=NA

[KLizotte]

The wind along the MVT during the warm weather months is nothing compared to what we get in winter. Consider it good training for next winter.

[baiskeli]

You know, in my face, and at the back of the rider going the opposite direction?

I recently moved and am using the MVT instead of the Custis Trail. It's a better commute but I am still getting used to the breeze. Would any of you MVT regulars care to describe what you've learned about the habits of the Adversary on the MVT? Which direction he usually travels and why, his seasonal patterns, and how to best him?

Perhaps it's a coastal wind. Water warms and cools more slowly than land. In the daytime, the land warms faster than the water. Air over the shore rises, and cooler air from above the water takes its place. The result is a sea breeze. At night the process reverses as the shore cools off more quickly than the water -- the warmer air is now over the sea.

Or not.

[Rootchopper]

In the winter months the winds tend to be out of the north and west. In the summer they tend to come from the south and east. Typically planes flying into DCA will fly into the wind (although for some weird reason they didn't for the last couple of days). If you are feeling strong and see a plane coming toward you on its descent, you have a tailwind and should get over yourself. Don't feel bad. Most of us fall prey to this delusion at least once a week.

You may also notice a change in wind direction in a few spots along the trail. The pinch point between DCA and the Parkway north of the terminals is odd because a tailwind can instantly become a headwind there. The other odd spot is the ramp at the Woodrow Wilson Bridge. It faces due west and can really have a beastly headwind as you ride up. You get no warning; you just slow way down and find yourself grinding away.

[Rootchopper]

So my last entry on this thread talked about winds out of the south and east in the summer. So why was I pedalling into a mighty headwind all the way to Rosslyn from Mt Vernon today?

[creadinger]

So my last entry on this thread talked about winds out of the south and east in the summer. So why was I pedalling into a mighty headwind all the way to Rosslyn from Mt Vernon today?

Yes it was indeed a mighty headwind this morning. We just had a big time cold front go through featuring northerly winds and cool Canadian air (when is it ever cooler than 85 here in the summer?). I think generally you can say that if the temp is warmer than average the wind will have a southerly component; cooler than average a northerly component. As that system moves away today the wind will back to westerly bringing all the hot air from the middle of the country - the low last night in Lincoln, NE was 80F, 83 in Dallas).

Another thing to consider is that meteorological winds are recorded at a height of 10 meters, which puts the instruments slightly above all the mess of surface features like trees, fences, buses etc... so wind at the surface will be far more variable than what you see on instruments. Also, those surface feeatures are great at funneling wind, deflecting it, reflecting it, etc.. For example the row of trees along the river north of gravelly point will deflect any W-NW wind to the south (in your face) as you head north on the trail. Bridges mess up the flow of wind quite a bit too.

[EasyRider]

Thanks for your posts, everyone. I avoided the headwinds today by taking the Pike to the Pentagon and on to the MVT instead of around Gravelly Point, but can't say I prefer it. For those into information graphics, I found an site that allows one to generate historical "wind roses" of conditions at DCA. It's a fun time waster. The strongest winds come from the north, but the wind blows most frequently, as many here have noted, from the south.

[elcee]

Also be aware of "apparent wind," which in short, is the vector sum of the wind and your bike's velocities.

http://en.wikipedia.org/wiki/Apparent_wind

Short answer: because you're moving forward at speeds comparable to a typical breeze, anything other than a tailwind +/- 45 degrees is going to feel like a headwind.

[TwoWheelsDC]

There is entirely too much smartness going on in here...it needs to stop, right now!