Adventures in Temperature Conversions

You may remember the complicated Fahrenheit-to-Celsius and Celsius-to-Fahrenheit conversion formulas. Or you may not remember them, but you may remember the fact that they are complicated, and involve 5/9 and 9/5, and adding or subtracting 32. But do you add (or is it subtract?) first, and then multiply, or do you multiply first, and by which factor?

Worry no longer, my friends! There is a much easier way to do it. The only formula you will need is the following:

T1 = (T2+40)*factor - 40.

The end.

This formula works for both temperature scales (so {T1,T2} = {F,C} or {C,F}). The only thing you need to remember is whether factor is 5/9 or 9/5. But that is not so hard: there are more degrees between freezing and boiling in Fahrenheit than Celsius, so when you convert to Fahrenheit, you need to use the bigger number, 9/5. Likewise, when converting to Celsius, use 5/9.

Does it really work? Yes! Let's do some examples.

Body temperature is 37 C or 98.6 F. Can we convert to those numbers? Let's start with C to F:

F = (C+40)*9/5 - 40

F = (37+40)*9/5 - 40 = 77*9/5 - 40 = 138.6 - 40 = 98.6

Now what about F to C?

C = (F+40)*5/9 - 40 

C = (98.6+40)*5/9 - 40 = 138.6*5/9 - 40 = 77 - 40 = 37

You can derive the traditional formulas for temperature conversion from this simple one.

F = (C+40)*9/5 - 40 = 9/5*C + 40*9/5 - 40 = 9/5*C + 72 - 40 = 9/5*C + 32

C = (F+40)*5/9 - 40 = 5/9*(F+40 - 9/5*40) = 5/9*(F + 40 - 72) = 5/9*(F - 32)

As easy as this formula is, it's still non-trivial to do in your head. So my sister Rachel told me an easy thing to remember about Celsius temperature ranges when it comes to the weather:

• 40+ C: extremely hot (=104+ F)
• 30-39 C: very hot (=86-102 F)
• 20-29 C: comfortable-hot (=68-84 F)
• 10-19 C: cool-comfortable (=50-66 F)
• 0-10 C: chilly (=32-42 F)

So the ideal you'd be most comfortable in is the range around 20-25 Celsius (68-77 F). From there you can see how much the temperature deviates from the ideal. (In Perth, once every couple of years it dips down to freezing, so I did not go any lower on the scale.)

Thoughts on a Rainy Saturday Afternoon

In the latest news:

• I ordered some new chairs for the dining room.  The table is old but serviceable, the chairs -- not so much.  Somehow they got sent to Oregon.  I don't know how that happened.  But the customer service representative set me up with a new shipment.
• We bought bunk beds for Vinny from a local furniture store, as a reward and incentive for sleeping in his own room.  Today, the delivery guys started putting it together only to discover that it was the wrong bed.  They had brought a double bed size bunk bed, not a twin size!  So, they had to take it back and reschedule us for delivery on Tuesday.  It was going to be a really cool bed, with bunks plus a trundle on the bottom.  Luckily, the trundle was the right one so they let us keep it and he is going to be sleeping on that for a few nights.  He is pretty excited about it, pretending that it was nighttime several times, so not all is lost.  I think he will be excited to stay in his own bed now (definitely a step up from a mattress on the floor).
• The toilet in our hallway bathroom stopped working.  The tank stopped filling.  Jeff successfully replaced the apparatus inside the toilet.
• Our kitchen sink faucet broke.  The stem unit inside the handle got bent up for some reason.  No problem, we could just get a new one, right?  Well, our faucet was relatively new, and the store doesn't carry the replacement parts for it.  So I ordered it online.  The total cost was $25, more than half of which was shipping.
• It is raining.  A lot.  I will be interested to see what the structural engineers say next week about our foundation.  The evidence of water seepage will be fresh.

Happy 1/11/11!

It is a pretty exciting day on the calendar today for those of us who love numbers -- all 1's (and notice my time stamp -- 11:11 pm).  I enjoy patterns like this even though the only meaning is that sufficient time has elapsed since the arbitrary starting date of our calendar system such that there are a lot of ones in the date.

In other news, we have had a lot of snow lately (where by "a lot of snow" I mean about three inches).  This has caused sufficient havoc that they even closed my workplace on Monday, and Vinny's school has been out for three days this week (another snow day tomorrow).  It was Vinny's snack day tomorrow, and I baked up some blueberry-banana muffins for school, which I now have to do something with since school was cancelled.

Winter Weather

It has been pretty cold here lately!  Why, today I don't think the temperature rose above freezing.  I excitedly wore several layers of clothes today.

It doesn't get quite this cold that often here in Tennessee.  The weather (although not the complete lack of snow) reminds me of my days in Illinois.

Speaking of Illinois, when I told Vinny that one of his cousins lives in Illinois, he suggested that his cousin actually lives in "Billinois" and just laughed like it was the most hilarious thing ever.  Then I suggested that Vinny lived in "Sillynois" and laughed a bit myself (although Vinny did not find that as humorous as his own joke).  I am still trying to figure out the four-year-old sense of humor.  So far it seems to me that watching him laugh is about the funniest part of his jokes.

Secret Message to the Weather

CHILL OUT!!!

Business Travel

Last week I was on business travel to our nation's capital. Now, as you all know, I hate travel, especially when it's business travel and not vacation travel. This was going to be a pretty long trip: leave home on Monday, return Friday night, and I was not feeling too happy about it. To make the trip more palatable, I arranged to have dinner on Wednesday night with one of my cousins who lives in the area.

As it turned out, a gigantic snowstorm was making its way towards the area. The meeting was shortened and we were to finish up on Thursday rather than Friday. Because of that, the organizers moved some sessions from later in the week to Wednesday night. To preserve my sanity, I skipped those sessions and had dinner with my cousin as originally planned.

The last question was, how to get out of there before the blizzard struck. On Wednesday, my airline was not letting people change flight plans without paying $800 for the privilege. So I called my work's travel agency and they reserved me a rental car (1/4 the cost of changing flights). I had two other friends in the same boat with the same airline, so driving home seemed both economical and doable. But just before we picked up the car, we thought we'd try one last time person-to-person at the airline counter. The folks at the counter had more of an incentive to let us change -- they were the ones who'd have to deal with us on Friday after our flights were canceled. So they agreed to change our reservations for free. We got home Thursday afternoon safe and sound, more than a day earlier than originally planned, and several hours earlier than I had anticipated based on driving.

SNOW!

They canceled school for the next day on Thursday night, but the snow didn't start to fall until Friday afternoon. I left work a little early to get home before the crazy drivers made the roads more dangerous. I took a different route than before (so as to avoid the aforementioned crazy drivers) and made it home just fine -- the roads were wet but not icy.

It snowed through the evening and all night, and we woke up to about 2 or 3 inches of the white stuff on the ground. We made a snowman -- this one was taller than Vinny, unlike the tiny one we made in December -- and shoveled the walks and the driveway.

Today the snow is melting, but it will do doubt freeze overnight and make for an interesting morning. I've looked at the local TV station website to find out if the public schools are canceled for tomorrow -- the preschool follows the public school schedule -- but so far they are still open.

SNOW!

So, we had some snow here yesterday afternoon. It's maybe 1/4 inch, tops, which wouldn't be that big of a deal to this former Illinoisian, except for two things: 1, the crazy Tennessee drivers, and 2, the ice. My normal 25-minute commute turned into a 90-minute commute last night. It took me 45 minutes just to get out of the gate at my workplace. I don't believe I've ever driven for so long in first gear. I had to take an alternate route as well, because when I saw the long line of cars backed up on the big hill where I turn left, I decided it would be prudent to keep going straight and take the long, roundabout way. Once I did that, I started to be able to drive faster than 5 mph -- up to 30 or 35 on the main road, which was wet but not icy. The most hair-raising part of my drive was actually driving down my driveway -- it is kind of steep and points down, so if it had been slippery I could have damaged my house in addition to my car. Luckily it was just fine.

My workplace is on a two-hour delay this morning, so I am not late (yet). I figured it would be smart to wait until the sun may have melted the stuff on my driveway before trying to back the car out.

Blizzards Are Good for Something

Tonight, in honor of my nephew's one-week birthday, we took advantage of the snow on the ground and made some winter treats.

First, my sister's better half and I both remembered the molasses candy from the Little House books. An internet search revealed this recipe. I don't have much experience with candymaking so I had to learn as I went what the different stages of sugar were -- we had to get the molasses and sugar mixture to hard crack stage and we didn't have a candy thermometer to work with. I think I got it to the right temperature, but it was hard to pour the stuff out in any kind of interesting designs.

Next, we made snow ice cream. We used snow, soy milk, sugar, and vanilla. That was really good too. I'd never had snow ice cream before, so it was fun to try it.

I told them, that's one advantage of living up north -- we could never make those things in Tennessee!

More News from the Night Shift

Apparently we may experience a blizzard here tomorrow. It will snow at least six inches, possibly more, and it may blow around a lot and cause white-out conditions. Also, there's a good chance that the high winds could knock out electricity. I'm glad I'm already here, and not having to contend with that. I'm hoping that everything will be clear by the time I leave on Sunday.

We brought a bunch of firewood into the house today, just in case the power goes out. We should be able to all huddle around the fireplace and keep warm. But if that doesn't work out, I'm sure that my baby nephew will give us top priority on getting emergency shelter somewhere.

Live from Urbana

I was concerned about the weather forecast for today, because snow was promised at home.  Now, normally, snow in East Tennessee is a joke -- that is, as long as you're at the lower elevations.  But today, I had to cross a mountain -- sure, go through a mountain pass, but still, it was a concern.

The promise of snow actually delivered.  We got about 1/2 inch in our yard.  We got Vinny dressed and went outside and played in the snow with him.  Because, hey, this was going to be one of the few snows of the winter!

I left home at about 11, when I figured the roads would all be clear.  And I had no problems over the mountain at all.  When I called Jeff later that afternoon, he said that all the snow had melted by 1:00 pm.  Once I got into Northern Kentucky, the roads were completely dry.  As I drove North, the temperature kept going down, but since the roads were dry I didn't really care.  My drive was completely uneventful, except for the fact that I had the radio cranked up and was singing at the top of my lungs in order to keep myself from getting drowsy.

I got to Urbana at about 6 local time, dropped off my stuff at my aunt and uncle's house, and went out to dinner with an old friend who still lives in Urbana.  We went to this Chinese restaurant that I had really missed, where I ordered "Ants Climbing Trees."  I'm not sure what's in it, but there are no trees or ants in this dish, just some combination of ingredients that tastes really good.  I got a chance to catch up on what my friend is up to as well as some local gossip.

Now I'm back at my aunt and uncle's house, waiting for them to get home.  I plan on sleeping in late in the morning, and then making my way to my sister's place sometime in the afternoon.  She and I will talk tomorrow, to coordinate.

Question of the Day

Who took the summer weather, and what did they do with it?

It feels like fall. I've been enjoying the beautiful weather, but it just feels wrong for this time of year. A high of 80 F? Unheard of, this time of year.

Maybe the cool trend will continue and we'll have an actual winter, with snow and stuff. That would be awesome!

Weather Update

The weather over the weekend was absolutely beautiful. It was sunny but cool -- I don't think the temperature ever got to 80º F! It reminded me of September more than July.

I kept the windows open all weekend. I really enjoy fresh air, and it's a rare treat that you can comfortably open your windows in July. I'm glad I got the chance this weekend!

Exploration Day

Yesterday was a really nice day. It was beautiful: sunny, but not too warm. Perfect for a family outing!

First, we went to the Aquarium of the Smokies. They have an exhibit where you walk through a glass tunnel and see sharks and other fish. At first Vinny was restless and didn't really like that exhibit but soon he got interested in looking at the sharks.

Then we had an early dinner before going into the park and seeing the Elkmont area. Elkmont was once a retreat for rich people to escape the oppressive summer heat in the city. When the national park was formed, instead of giving up their land they were paid a reduced amount of money and given long-term leases on their property, the last of which expired in 2001. We saw many of the former vacation homes, a number of which were in ruin. The area was placed on the National Register of Historic Places, though, so the ones that are salvageable will be preserved. I don't know what their plans are -- perhaps it will be something like Cade's Cove.

Yesterday was a fun day out with my boys. Today, by contrast, was cold, rainy, and overcast. We spent the day indoors.

Sunny Saturday Afternoon

Today was so beautiful that we had to get out and do something. After a week of below-freezing temperatures, today was sunny and warm and there was no excuse not to spend some time outdoors. So we went to the Museum of Appalachia, a 60-acre living history museum about the history of Appalachia.

They have a large collection of historical buildings brought in from across the region, and historical artifacts from the era. They also have a lot of animals, including sheep, turkeys, chickens, and peacocks. Vinny enjoyed running around and looking at the animals and buildings. Unfortunately there were a lot of really interesting objects everywhere that he was not allowed to touch, which detracted from the experience for him somewhat.

But it was a lot of fun to get out and enjoy family time in the sunshine on a leisurely Saturday afternoon.

How's the Weather?

It's been kind of crazy here lately.  At the beginning of the week it was warm, but then it rained a lot and cooled down.  Then, there was a lot of wind, which made it even colder.  It's downright chilly tonight, down in the 20s.

That sounds totally wimpy to many readers, and I completely agree with you -- in principle, at least.  But for Tennessee, it's cold.  And when you're no longer used to 20 F weather, it feels really cold.

Back from the Conference

Did you miss me, O Vast Readership?

We left for Atlanta on Tuesday afternoon. The trip down was uneventful, until we got off the interstate and tried to find the hotel. Construction made things more complicated, but we were able to navigate to the hotel without too much of a challenge.

The conference went well -- I presented on Wednesday afternoon, and got some good questions. I went to a number of interesting talks, a number of boring talks, met some new people, and caught up with longtime friends. I talked to a lot of people about a lot of different things, including load balancing, high-performance computing education, and the latest gossip from my old department. I made some new contacts -- staff members at other labs, professors at various universities, and students who will soon become colleagues.

We were planning to spend today at the Atlanta Zoo or the Aquarium, but the inclement weather made us change our plans. Last night it was extremely stormy -- a tornado damaged a large piece of downtown, 10-15 blocks south of where we were staying -- and more storms were supposed to arrive by 11 a.m. So we headed home this morning, driving through some heavy rains, but making it home safely in the early afternoon.

Winter Weather

After going from Illinois winters to Tennessee winters, I now understand how my Wisconsin-native parents felt about Kentucky winters. They're wimpy! It just doesn't get cold. The first two winters here, I kept wondering when winter would actually come. It felt more like a prolonged autumn.

I would laugh at my Tennessee-native friends and colleagues, who would bundle up at the first sign of the temperature dipping below 50. Those first two years, I would occasionally don thermal underwear, but I never got out my super heavy Illinois coat.

The past two days, however, have been remarkably cold for Tennessee. The temperature did not make it above freezing at all, and in the morning on my way to work, the temperature was in the teens. So I pulled out the Illinois coat and gloves, and felt pleasantly nostalgic. Okay, so the low temperature (14 degrees yesterday) was a temperature that would pass for a high in Illinois, but it felt good to don the accoutrements of cold weather, zip up that coat, and fumble with my keys through the thick gloves.

Great Invention Idea

So, our air conditioner has been out since Monday. I don't think it's anything big; the repair person is coming today, and while any HVAC repair is not cheap, it shouldn't be too outrageously expensive. I think it just needs more coolant.

Anyhow, the lack of air conditioning has made it pretty hot in the house. I've opened the windows at night, to let the cool air in, and by morning the house is pretty cool. Yesterday morning it was 77; today it's 80. But this has made me realize that if we had a more efficient method of exchanging the air inside our house with the air outdoors, we could use a lot less energy for air conditioning.

Yes, there exist whole house fans, and that would help, but that's not all that I'm talking about. I think it would be useful to have an intelligent house with a hybrid HVAC system. Here's my idea.

You would provide a range of temperatures that you would consider acceptable indoor temperatures, let's say 68-80ºF, and an ideal temperature, let's say 78. Your house would shut all the windows and turn on the air conditioner, targeting your ideal temperature, when the outside temperature was too high to maintain the house within your range. Otherwise, the house would open windows, exchange the indoor air with outdoor air using your whole-house fan, close and shade windows on the side of the house where the sun is beating down, etc.

And the system could do the same sort of thing in the fall and winter: shut all the windows and turn on the heat at night, and then harness the warmth of the air outside during the day when it could.

If we had a system like that, I think we'd need to run the air conditioner only for a couple of hours during the day. But as it stands, even though it's 61º outside right now, the temperature in the house is 80, and if our air conditioning system were working, it would be running right now. What a waste!

Al Gore, Climate Change, and Computing

We watched An Inconvenient Truth for the first time about a month ago. I thought it was a really good movie. I've always admired Al Gore (and I voted for him in 2000, I'm not ashamed to say).

I can't imagine how much it must have hurt to have won the popular vote but lost the election. But I was really glad to see that Al Gore has bounced back, and found his calling in spreading the word about global warming. It's something he's obviously passionate about and that he loves to share. It warmed my sentimental heart to see him doing something so wonderful. (My inner mom wants to give him a hug and kiss the top of his head, and tell him how proud I am. Something tells me that the Secret Service wouldn't let me close enough to do the deed, though.)

If you haven't yet seen An Inconvenient Truth, I'd encourage you to do so. Global climate change is an incontrovertible fact. I know a lot of folks who work in the climate modeling area, and their only agenda is to find out the truth. Nobody wants climate change, but the evidence and the models are a smoking gun. The people who model the climate use the same sorts of numerical methods that are used to model cars, airplane wings, and even our nuclear stockpile. Anyone who flies on a plane or drives a car should put as much faith in climate models as they do in finite element models of cars and airplanes.

One interesting aspect of these climate models is that they're modeling a dynamical system, meaning that a lot of effects are not linear. In other words, small perturbations can result in large changes in the system. So they start the climate models with slightly different sets of initial conditions, and run them and come up with a range of possible outcomes. That's why the predictions give a range instead of an exact value at the end.

Climate modeling takes up lots and lots of time on the supercomputers. They regularly run on thousands of processors for days at a time. As the supercomputers have gotten more powerful, they have refined the scale and added more elements to their models. It's really fascinating work, although it's not something I've ever been involved in. But the climate models could always use some load balancing, I'm sure, so maybe I could help them with that at some point!

New Science magazine has an interesting feature on climate change available online. If my meandering stream-of-consciousness discussion of Al Gore and the strange maternal pride I feel for him, climate change, and computer modeling hasn't convinced you (and why would it?), then I encourage you to check their article out.