Clouds represent a fabulous form of flow visualization that is available to everybody, almost every day. Here is a good online cloud gallery:
Cloud Appreciation Society: British site (now international, but with Brit humor) for cloud lovers, including a gallery of clouds that look like things.
Here are some resources to help you figure out what the clouds have to say about flow physics.
Inexpensive books on clouds:
Cloudspotter’s Guide, by Gavin Pretor-Pinney, founder of the Cloud Appreciation Society (2006). This is a very gentle introduction to cloud physics, with interesting anecdotes about each cloud type.
The Cloud Book by Richard Hamblyn, in association with the Met Office, 2008. A well-illustrated cloud atlas, organized by cloud height
The Book of Clouds by John Day (“Cloudman”) 2006. Another well-illustrated cloud atlas, but organized by cloud family (cumulus, stratus etc.)
Book on cloud flow physics:AC No. 00-57 Hazardous Mountain Winds & Their Visual Indicators: This is an FAA book for pilots on mountain area clouds and the winds that they reveal. You can download the whole short book for free.
Cloud Types for Observers: This is a 45 page document from the Met Office (2006), the British weather bureau. This booklet describes how to classify clouds. You can download the whole short book for free.
Current Skew T Plot for Denver. This shows the current temperature profile in the atmosphere. If the temperature (white line on the right) is steeper than the adiabatic cooling line (solid yellow) then the atmosphere is stable.The 6 am Denver sounding will have a timestamp of 1200z, and the 6 pm sounding will have a timestamp of 0000z, with the next day’s date. More info on skew-T plots can be found here. If you are really serious, here is a detailed free online course, Skew-T Mastery. Here is a skew-T archive that covers back to 1973. Be sure to choose skew-T plot as output option.
e-Wall, Penn State’s Electronic Map Wall. Forecasters synthesize a local forecast from the predictions of several computer models. This site shows the big model predictions, plus a range of other weather data, such as satellite views and upper air plots.
PSD Map Room. More weather data and model predictions, from the NOAA-CIRES Climate Diagnostics Center, including polar views.
Fluid Physics for Flow Vis is a group library on Zotero that has science references for the most popular types of flows that students create. Anybody can see the citations but you’ll have to email me to get access to the actual articles.
Propylene glycol is the main ingredient in food coloring. This link lists its density, safety and some other properties.
Rheoscopic (aka kalliroscopic) fluids show the shear field in a flow. Pantene Pro shampoo is an example of a viscous, pearlescent fluid with this property. You can make your own inexpensive fluid using an iridescent art pigment, such as Pearl Ex pigment, available in art supply stores.
There are a number of flow visualization galleries, both on the Web, and in other publications. Here is a sampling:
FYFluidDynamics. I can’t tell you what the acronym stands for, but it’s an excellent blog that gives concise explanations of flow vis images and videos, by Nicole Sharp.
eFluids: A free resource for fluid dynamics and flow engineering, with a large image gallery, and experiments to try.
The Gallery of Fluid Motion, a juried show of flow images held at the annual American Physical Society Division of Fluid Dynamics meeting. Here is a book of images collected from the Gallery over the past 17 years.