Air density and TT times

Just a quick one for the masses.
I’ve been doing my TT efforts in the dark at 5:30am-5:45am here in NZ at sea level.
My times have been slower than I would have bought, but my power is better than ever.

Is the air denser early in the morning compared to later in the day.

Both days the weather and wind has been very similar . Equipment/position allotetty much the same.

It just seems slower, any thoughts?


I’ve added a link to help you calculate air density for your area. Cooler air is more dense, hot humid air is less dense.

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And if you know the air density and how it changes, then this:
will give you effects on speed, for given cadences and gearing.

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Brilliant - I have just done a couple of cold TTs over here in the UK and was wondering what effect the temperature difference, air pressure and density had compared with last year. Well timed post, thanks.