If you like this graph and associated commentary, remember to check out the rest of my graphs on this blog, here: Graphs of the Day
So why graph number 36 without graphs 32-35? Have I forgoten how to count? Am I having a brain fumble right now? … Well, I can’t rule any of those out, but no; I just thought that this one needed to be published while we are still in the grip of that most merciless of seasons: Spring.
I have friends from different walks of life, but there’s something very comforting about discussing the weather with engineer friends at work, and being able to say things like “yeah, you intuitively expect it to be a nice analogue S-curve, but in reality it’s more like a bulls**t PWM output, that makes it impossible to give the kids the right amount of bedding”… and they just nod in agreement and I don’t have to spend the next 5 minutes at a whiteboard explaining myself.
Also, climate change is real.
You should listen to the experts who study the climate, as they are actually the only experts on the topic, and peer reviewed publications are the most reliable methods for sharing their knowledge, as it lets other experts in the field disagree and\or comment. Also, there isn’t really any money in climate change, so most of the vested interest is on the side of burning fossil fuels… no-one ever got rich by studying in academia.
Also, even companies that DO have a vested interest in denying climate change are acknowledging the issue (Shell, South32, etc)… I mean, mostly their reponse is a bit soft, because they have a vested interest, but they acknowledge that it’s a disasterous issue… Look, we all need to do better, okay? Just acknowledge the problem and work harder, everyone.
Graph Number: 36
Graph title: Spring in Brisbane
X Axis: Season
Y Axis: Temperature
General shape of graph: S-curve + PWM digital equivalent
How it works: This spring in particular seems to have had a lot of up-and-down weather. Rather than the days gently increasing from cold winter, through warm winder to hot summer, it seems to have been jumping from winter to summer, then back. the duration of these excursions from cold to hot seems to have been increasing in duration, to the point that now hot is the norm and then we’ve had the occasional brief cold snap… this is called Pulse Width Modulation. The signal is either on or off, and it pulses on for a certain portion of each cycle (the cycle period remaining constant). As the width of the pulse increases, the average value increases in the same proportion. If the cycle duration is short enough, compared to the response of the system, this is a really great way of using a digital control system to control an output. The inertia of the system means that the output is smoothed out, so you see it as a linear change in value. Good applications are:
- Controlling the torque\speed of a DC motor.
- Controlling the heat of an oven, sous vide, 3D printer nozzle or other heater that needs to achieve a temperature set point.
It’s not a good method for controlling the weather, because I like to be able to wear the same jacket each day, and use the same type of blanket on the kids bed for an extended duration without worrying if it’s now too cold for them.