What a difference two hours makes…

Well, we are in Lubbock. More posts to follow soon about the new house we are renting and whatnot but first I want to talk about the climate here. Specifically we should talk about the incredible temperature changes that occur every morning.

Yesterday we decided to go for a run for the first time down here. I had checked the temperature outside around 9 am and it was a very pleasant 72 F. We had breakfast, planned the day, and by the time we actually stepped out the door it was 11:30.

I generally pride myself in my ability to run in the heat. I would often go for a run in Lafayette when it was 90 F and 60% humidity. This though was bloody hot. Lets look at why!

Temperature variation for a typical August day in Lubbock.

Here I have posted the temperature over time for a typical day in Lubbock. The temperature is in red, heat index is in yellow, and the dew point is in green. There are several fascinating things on this plot. The first is that the heat index is below the actual temperature. The relative humidity is not plotted here but is evidenced by the very low dew point. At no point does the ambient temperature ever even get close to the dew point which means that here, at least in August, *the dew never falls here*.

That, while weird, is not what I wanted to show you. What I want to show you is that the temperature here varies by 30 degrees over the course of 8 hours. That is 4 degrees an hour, or 1 degree every 15 minutes…. What!?

More interesting is the fact that it cools down just as much. Lets compare this to Lafayette’s temperature plot:

Temperature variation for Lafayette.

In Indiana, the temperature varies by 20 F, heating up less and cooling down less. Why is this?

<<Insert Geek Out>>

First, lets talk about why Lubbock heats up more:

  1. Visibility: the air is clearer here. Small particles in the air, either due to industrial emissions, higher humidity, or plant emissions (pollen, sap, ext… ) will scatter light and lower the light intensity/energy that reaches the surface.
  2. Latitude: Lubbock is closer to the equator. The sun sits higher in the sky so, again, the amount of energy that hits the ground is greater.
  3. Elevation: Lubbock is higher! When there is less stuff between you and the sun, again, more energy reaches the surface.

Lubbock also cools down more quickly for exactly these same reasons. The only way for the earth to cool down is through radiation, thermal radiation into space. The less stuff in between the earth and space, the more quickly it cools down. In this case, water vapor and cloud cover are important barriers to thermal radiation (so is CO2, but that concentration is roughly the same between Lubbock and Lafayette. To be clear, Lubbock also cools down more because there is less CO2 simply because there is less air between us and space ).

<<End Geek Out>>

All that to say… Lubbock actually does get hot and there is a reason people do stuff outside before 8 am and after 8 pm.


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