Don Cass

December 14, 2011

12/14/11

Filed under: Running blog — doncass @ 5:33 pm

OK, I’ve never tried a real blog before… let’s see what happens…

It’s Wednesday, Dec 14th. Chilly morning, but no snow to be seen.

First I searched around online trying to find out why it’s colder on nights with no wind…. It turns out it’s apparently because thae air cools mostly by conduction to the ground, not by radiation to space. As the ground loses heat by radiation, it cools & thus cools the air in contact with it. So the air cools from the bottom up. Without ind, the coldest air is near the ground – where we are. A bit of a breeze allows the colder air near the ground to mix with warmer air UP HIGHER (!) so the air near the ground isn’t as cold. Cool eh?

In the process of finding the answer to #1, I also realized taht “cold air sinks” for TWO reasons. For one thing, the density of a gas increases as T decreases. But colder air can also “hold less moisture” than warmer air – and water (H2O, MW=18) is lighter than air (mostly N2, MW=28), so drier (colder) air is actually denser than moister (warmer) air. I guess I need to compare the density changes due to T  and to water content. If anyone does this before I get to it, let me know….

Then I moved on to reading the sections of my Modernist Cuisine book that discusses food safety….in preparation for including more on this topic when I next teach Chemistry of Cooking. It’s pretty interesting….First, some food-boune illnesses are actually caused by microbes – most of which are introduced by improper hand washing (so I ordered surgical scrub brushes as Xmas presents!) Other food-bourne illnesses are the results of pathogens produced by microbes – many of which are much harder to deactivate than the microbes. And, finally, many microbes form spores when subjected to heat, etc – and these spores start to propagate when cooled. This makes cooking “safe food” actually sort of tricky. It turns out the “cook food X to a temperature of Y” is a gross simplification. Much lower temperatures are capable of killing pathogens – if the food is held there long enough. (This is the basis of long-time “sous-vide” cookery – where you keep the food vacuum-sealed at a temperature low enough that it doesn’t dry out – but for a long enough time that it kills pathogens. ) So… I started making a spreadsheet of the common pathogens responsible for food-boune illnesses…

Then I went into the lab to sign some students’ time-sheets so they can get paid, I did a bit more work on cleaning up our chemicals… Went through a bunch & decided which could go (and how) and which might be worth keeping….

Then it was off to buy food… Got Kili some of Junior’s dog-food that he liked so much.

Then home and put together a syllabus for next term’s organic chemistry so I can try to coordinate labs with Cristy. It’s so hard to know how fast to actually go through material…

Then took Kili for a walk down the road – and met up with Echo (the Bernese Mt Dog next door) and they played while I got a tour of Bunny & Mo’s house (with a birch ‘xmas-tree’ – just like we were thinking of). Turns out that  they’re heating with a wood cook-stove like the one we used to have – but I think they’re heading a much smaller space so it’s probably more practical for them. They have a great view (and roof access) from their 3rd floor ‘tower’ – makes me wonder about opening up the view in our highest loft…maybe some day.

Suzy’s off to a ‘last class’ dinner in Orono with this education class that she’s been taking. So I guess I’ll rummage through the fridge, throw out stuff that should be thrown out & heat up some leftovers for dinner… When she gets home we’ll watch Survivor (it’s getting to be the end of the season) and call it a day….

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