Fahrenheit and Celsius

The two primary temperature scales of Celsius and Fahrenheit side-by-side calling out water freezing, body temperature and water boiling

Prints

The two most commonly used temperature scales are Celsius and Fahrenheit. The Celsius scale, named after Swedish astronomer Anders Celsius, sets 0C at the freezing point of water and 100C as the boiling point of water at 1 atmosphere of pressure — normal air pressure at sea level. The Fahrenheit scale has 32F as the freezing point of water and 212F as the boiling point. With 180F between freezing and boiling that means each degree Celsius is 1.8 degrees Fahrenheit.

Several accounts of the creation of the Fahrenheit scale exist but the general gist is that Daniel Fahrenheit set 0F at the freezing point of a brine mixture, 32F at the freezing point of water, and another point at body temperature around 96F (now 98.6F). He divided up the scale between these points giving a scale with helpful resolution.

It's interesting to think that for most of history, there was no comparable way to say how hot or cold something was.

Having spent time on both sides of the Atlantic I've tried to get at least somewhat familiar with both of them. To convert between them in my head, at least around most air temperatures, I use a quick approximation. As 32F is 0C, and for each one Celsius you move almost two Fahrenheit, you can roughly go from Fahrenheit to Celsius by subtracting 32 and dividing by 2 (or a little less to be closer). So 50F is approximately 9C (actually 10C), or 86F is approximately 27C (actually 29.4C). It's not perfect, but it's often good enough if you're trying to work out if it'll be hot out. To go from Celsius to Fahrenheit, it's the reverse, times by 2 and add 32.

There are also at least two simple anchor points that can help just by swapping the digits around:

82F is near enough 28C
61F is near enough 16C

Both scales are now defined relative to the Kelvin scale, which sets the lowest point of 0K at absolute zero, where basically all movement stops. Zero on the Kelvin scale is around -273C. As such, the Kelvin scale, though helpful for scientists, is not very practical for discussing the weather.

Published 5 Feb 2023

A weekly sketch by email

Learn something new in a sketch each Sunday

Sketchplanations in a book! I think you'll love Big Ideas Little Pictures

Prefer to listen?
Try the podcast

Like Sketchplanations?
Support me on Patreon

Keep exploring

Isometric projection is a simple way to draw 3D shapes. The meaning of isometric is "equal measure," from the Greek words iso- for equal and metric for measure. So, in an isometric drawing, all three axes, x, y, and z, are scaled equally, giving a clear, undistorted view of an object in three dimensions. Except that isometric drawings can look a little odd and oversimplified. This is because of the lack of perspective, a visual distortion of 3D shapes we experience in the real world. In a perspective drawing, parallel lines converge in the distance towards a vanishing point, but in an isometric drawing, parallel lines stay parallel, and sizes don't get smaller in the distance. The lack of perspective in an isometric view can make it look artificial, but it always looks clear. I learned isometric drawing when studying engineering. Armed with a stack of isometric paper with a printed isometric grid, we had to reel off exercises involving drawing isometric views of 3D objects. And isometric projection is really handy for this. It can take a long time to build the skills to sketch a realistic 3D-looking object, perspective and all, but with isometric paper, you can quite quickly produce something that communicates to you or others what's in your head or on the workbench. Isometric projection is handy for boxy shapes—I chose an approximation of the Bauhaus Dessau building by Walter Gropius to show it. If you need curves and angles, just like with perspective drawings, it can help to draw more boxes around these areas and use them to align your curves and meeting points for your lines. Isometric views and their variations have had somewhat of a resurgence of late in video and board games. It turns out they're pretty helpful in map-based or city-building games such as Zynga's Farmville, Civilisation, or Sim City as the isometric view allows all parts of a scene to be viewed equally—in the distance or up close—while still seeing every detail in, say, a building, wherever it is. If you want to try some isometric drawings, making your own isometric grid paper is easy. Just draw equally-spaced vertical stripes and then a criss-cross of lines in both directions at 30 degrees from the horizontal. This gives a host of equilateral triangles and an easy base to start drawing your 3D objects. Or just download some templates online. You'll find that building up more complex shapes out of cubes is dead simple if you keep to the lines on the isometric grid. Just as in the drawing here, sometimes shapes drawn in isometric view lend themselves to curious optical effects. The lack of perspective can make the difference between heights and depths ambiguous. So, you can't always tell if two surfaces are at very different heights or if one is in the distance. The brilliant puzzle game Monument Valley uses this quirk of isometric projection to create mind-bending puzzles that are well worth a try. For instance, rotating a high surface can suddenly make a platform that extends far into the distance 🤯. Isometric-like projection can also help make impossible shapes, such as the Impossible Staircase, or Penrose stairs. Another type of projection, anamorphosis, creates a drawing that only looks correct from a particular viewpoint. Anamorphosis leads to some remarkable street art. Also see: 2.5D objects, including an old video of me drawing a sketchplanation Orthographic projection One-point perspective Two-point perspective Three-point perspective Atmospheric perspective Anamorphosis The Impossible Staircase, or Penrose stairs When drawn nice and faint, the isometric grid is an example of a ghost grid Isometric projection is quite the opposite of "draw what you see, not what you think." Foreshortening can be hard to get the hang of. Life is 3D—give edges thickness…Isometric projection is a simple way to draw 3D shapes. The meaning of isometric is "equal measure," from the Greek words iso- for equal and metric for measure. So, in an isometric drawing, all three axes, x, y, and z, are scaled equally, giving a clear, undistorted view of an object in three dimensions. Except that isometric drawings can look a little odd and oversimplified. This is because of the lack of perspective, a visual distortion of 3D shapes we experience in the real world. In a perspective drawing, parallel lines converge in the distance towards a vanishing point, but in an isometric drawing, parallel lines stay parallel, and sizes don't get smaller in the distance. The lack of perspective in an isometric view can make it look artificial, but it always looks clear. I learned isometric drawing when studying engineering. Armed with a stack of isometric paper with a printed isometric grid, we had to reel off exercises involving drawing isometric views of 3D objects. And isometric projection is really handy for this. It can take a long time to build the skills to sketch a realistic 3D-looking object, perspective and all, but with isometric paper, you can quite quickly produce something that communicates to you or others what's in your head or on the workbench. Isometric projection is handy for boxy shapes—I chose an approximation of the Bauhaus Dessau building by Walter Gropius to show it. If you need curves and angles, just like with perspective drawings, it can help to draw more boxes around these areas and use them to align your curves and meeting points for your lines. Isometric views and their variations have had somewhat of a resurgence of late in video and board games. It turns out they're pretty helpful in map-based or city-building games such as Zynga's Farmville, Civilisation, or Sim City as the isometric view allows all parts of a scene to be viewed equally—in the distance or up close—while still seeing every detail in, say, a building, wherever it is. If you want to try some isometric drawings, making your own isometric grid paper is easy. Just draw equally-spaced vertical stripes and then a criss-cross of lines in both directions at 30 degrees from the horizontal. This gives a host of equilateral triangles and an easy base to start drawing your 3D objects. Or just download some templates online. You'll find that building up more complex shapes out of cubes is dead simple if you keep to the lines on the isometric grid. Just as in the drawing here, sometimes shapes drawn in isometric view lend themselves to curious optical effects. The lack of perspective can make the difference between heights and depths ambiguous. So, you can't always tell if two surfaces are at very different heights or if one is in the distance. The brilliant puzzle game Monument Valley uses this quirk of isometric projection to create mind-bending puzzles that are well worth a try. For instance, rotating a high surface can suddenly make a platform that extends far into the distance 🤯. Isometric-like projection can also help make impossible shapes, such as the Impossible Staircase, or Penrose stairs. Another type of projection, anamorphosis, creates a drawing that only looks correct from a particular viewpoint. Anamorphosis leads to some remarkable street art. Also see: 2.5D objects, including an old video of me drawing a sketchplanation Orthographic projection One-point perspective Two-point perspective Three-point perspective Atmospheric perspective Anamorphosis The Impossible Staircase, or Penrose stairs When drawn nice and faint, the isometric grid is an example of a ghost grid Isometric projection is quite the opposite of "draw what you see, not what you think." Foreshortening can be hard to get the hang of. Life is 3D—give edges thickness

Newer

RRandom

Older