can any one explain DA to me?
can any one explain DA to me? can any one explain DA to me? and what is a positive DA and negative DA? i want some one to give me a feeling of the meaning of the DA.
thanks.
thanks.
DA = Density altitude.
Basicly it is a number that equates weather and altitude together to give you an idea of the conditions you are running in.
Last time I was out at Bandimere the DA was 7200 early in the day and even higher in the afternoon. The actual altitude of the track is 5800 feet.
But it was like being at 7200.
If that makes any sense.
Basicly it is a number that equates weather and altitude together to give you an idea of the conditions you are running in.
Last time I was out at Bandimere the DA was 7200 early in the day and even higher in the afternoon. The actual altitude of the track is 5800 feet.
But it was like being at 7200.
If that makes any sense.
Its a way of leveling the playing field and giving us a way to talk about track conditions in a comparable way. Given a fixed set of weather conditions the density of air is much higher at sea level that at higher altitudes. You can literally think of it as a column of air with the weight of all mollecules above it compacting those at the bottom. More o2 mollecules at sea level give you more power and better combustion. The fact that weather conditions aren't the same at all locations makes this a bit trickier. Higher temps cause mollecules to spread out making the DA actually higher than it is. Take HRP in Houston for example. It sits at about sea level so guys run amazing times there. On a hot humid day the DA at HRP can become higher than its actual elevation causing you to run worse because you are getting a "weaker" charge of air. This is why the DA was worse in the afternoon in the earlier post. On a cool morning with lower humidity in the fall the DA can actually dip into the negative range meaning that the conditions are very favorable for good times due to the low altitude of the track and fact that colder air is more dense. Hopefully this helped to explain the basics of DA. To find DA you need to know the current altitude, barometric pressure, and dewpoint. A calculator can be found here.
http://www.csgnetwork.com/densaltcalc.html
Lower is better.
http://www.csgnetwork.com/densaltcalc.html
Lower is better.
as i know as we go higher the density of the air becomes less and less and this is not good for horspower. so does that mean i have denser air at 1200 DA than at 5700 DA?
what about the negative DA does it mean it is below sea level and the air is denser than even at sea level? is that correct? or the densest air is at 0 DA.
thanks.
what about the negative DA does it mean it is below sea level and the air is denser than even at sea level? is that correct? or the densest air is at 0 DA.
thanks.
Originally Posted by cenTX-LS1
Its a way of leveling the playing field and giving us a way to talk about track conditions in a comparable way. Given a fixed set of weather conditions the density of air is much higher at sea level that at higher altitudes. You can literally think of it as a column of air with the weight of all mollecules above it compacting those at the bottom. More o2 mollecules at sea level give you more power and better combustion. The fact that weather conditions aren't the same at all locations makes this a bit trickier. Higher temps cause mollecules to spread out making the DA actually higher than it is. Take HRP in Houston for example. It sits at about sea level so guys run amazing times there. On a hot humid day the DA at HRP can become higher than its actual elevation causing you to run worse because you are getting a "weaker" charge of air. This is why the DA was worse in the afternoon in the earlier post. On a cool morning with lower humidity in the fall the DA can actually dip into the negative range meaning that the conditions are very favorable for good times due to the low altitude of the track and fact that colder air is more dense. Hopefully this helped to explain the basics of DA. To find DA you need to know the current altitude, barometric pressure, and dewpoint. A calculator can be found here.
http://www.csgnetwork.com/densaltcalc.html
Lower is better.
http://www.csgnetwork.com/densaltcalc.html
Lower is better.
so the DA is like a mix of altitude, temp, pressure, humidity....etc measurments compacted in one number that gives idea of how dense the air is.
Last edited by Abdullah; Jun 11, 2006 at 12:21 AM.
Originally Posted by Abdullah
as i know as we go higher the density of the air becomes less and less and this is not good for horspower. so does that mean i have denser air at 1200 DA than at 5700 DA?
what about the negative DA does it mean it is below sea level and the air is denser than even at sea level? is that correct? or the densest air is at 0 DA.
thanks.
what about the negative DA does it mean it is below sea level and the air is denser than even at sea level? is that correct? or the densest air is at 0 DA.
thanks.
