About

Why "Eat Live Clouds"?

I choose to pronounce the "live" in my blog title as in "alive" not "live" that rhymes with "give". Perhaps this is because I want to understand clouds, and I see understanding as a type of consumption. Furthermore, cloud droplets may in fact be micro-habitats for microorganisms. So when you are in the mountains breathing fog, you may be eating a cloud alive!

Test

Test

GigaLES cross section

I haven't posted in a while, but I've done a lot of work leading up to the Workshop on Physics in Weather and Climate Models hosted at Caltech by JPL's Center for Climate Sciences and the Keck Institute for Space Studies. I learned so much at this workshop, it will take a bit of work just to put together everything I've worked on and learned and been writing about these past few weeks, but for now, here is an animated post showing a cross-section of MSE in the GigaLES, each frame is 5 minutes apart. Here are links to versions of the following figures running slower so more details can be observed.

http://www.inscc.utah.edu/~glenn/cross_sec/ysec1_500.gif
http://www.inscc.utah.edu/~glenn/cross_sec/ysec1_w_500.gif

Note a few details like: The horizontal : vertical scale is squished, features are about 4 times more skinny than a 1:1 image,  the time in hours:mins is displayed in the top left corner, the buoyancy oscillations at the top of the MSE frame from 7:00 to 8:00 hours, the dramatic increase in MSE that rising blobs experience above the freezing level (~5km) due to latent heat of fusion increasing the temperature, therefore increasing the buoyancy, and the vertical velocity, shown in the animation below the MSE frame.

Laser Diffraction Demonstration

Laser Diffraction Demonstration

Hi there!

Here is a quick and dirty overview of a demonstration I had in mind, using photos to show the coolness! Also they show that I'm still here at 8:40pm...

First, give the kids these cool glasses. I'm sure that'll take a few minutes. I have about 50 of them.

They make everything look like crazy rainbows! That'll probably take a few minutes more with the students.

To take the above photo I just put the glasses over the lens and sparked a lighter. Any point source of light looks really cool through them, the point source is split into all the colors that are composing it.  Looking at a strand of multi-colored christmas lights (not pictured) you can see the spectrum coming from say, a red bulb, isn't pure red, but contains some other colors that aren't being seen unless they are spread out in a spectrum through the glasses. You can also see the same thing for a blue bulb, but what is coolest is comparing the rainbow spectrums and noticing that the blue bulb spectrum is strong in the blue and the red is strongly red... they look like different types of rainbows I guess... hard to describe. The glasses are two layers of diffraction grating at 13,500 lines of dark, clear, dark, clear etc. per inch. It is cool they look so clear, but the grating is very small, so that's why it works. 

At this point would probably be some talking to the kids, explaining about the glasses, then I'd like to touch on how/why light can be interpreted as a wave. I would point out to the class that light obviously isn't a wave, it's color, right? Look at this green laser, it's not a wave, it's green!

But that doesn't have a lot of utility for explaining some of the things light does. I would then shine the green laser through the glasses, showing the effect:

The green laser light is projected as a grid! Why? Before the glasses just spread out all the colors into a rainbow... why isn't the green all spread out like that? Why are there dark spaces in between the green dots?

This would probably be a good time to ask the class if they can think of anything else they've ever seen that behaves like this, what gets spread out after it squeezes through a small space? I would say it's almost like the light is "splashing" as it goes through the small grating of the lens. Then maybe we would talk about the difference between saying light is a wave and saying light behaves like a wave.

Then we could talk about what different kinds of waves there are, really big long ones, really short fast ones. Then I'd claim that maybe different colors of light behave like different size waves, and ask the class to make a prediction about whether bigger waves will splash farther apart or not as far apart as a smaller wave through the same size opening. Hopefully it will be easy to show that longer waves splash farther. 

I could ask a student to guess, if light is a wave, and different colors are different size waves, if you had to guess, which colors are "longer" waves than others? What is it about red or blue or green that could clue you in to whether it was a bigger wave or not? Perhaps some kid will come up with a good reason, but I can't think of one, I'd like to bring it up to point out how some aspects of nature are hidden from us through normal experience.

Then it would be experiment time to prove our guesses! I would set up a little stand I have to hold the glasses and shine the green laser through to the board and have a student use a green marker to mark the location of the dots. Then we would shine a red laser through the lens up at the board and have a student mark the locations with a red marker.

It's a little dimmer, but I'm sure lining up the middle 9 would be good enough to show that the red laser is being spread out farther than the green laser. Then we could point out that if you say longer waves splash farther this is the only reason to say red is a "longer wavelength" than green, because of its behavior, not something about "red" as an experience itself.

At this point the demonstration would be over. If the kids were up for it, we could measure the spread of the dots on the board, and knowing the distance from the laser to the board and the width of the lens grating, we could calculate the relative wavelengths of red to green light. The equation would be simple algebra, just some division.

Sunset Saturday

The view from my office at sunset as a cold front blows dust around:

Transform to Entrainment Form

This post is a summary of the method I use to transform MSE spectrum mass flux histogram data to a form using a model of entrainment so that entrainment rate is on the abscissa, not MSE.

Note that the MSE spectrum mass flux histogram data represents the NET mass flux occurring at a particular MSE. If one parcel with a MSE of 340 K is moving up by 1 m/s, and another 340 K MSE parcel is moving down by 1 m/s, the net mass flux is zero. Let us consider only those MSE values with positive net mass flux, as shown in the figure below. Also plotted is a black line representing the saturation MSE which I will refer to as h*. Not it is found at each level by calculating the average temperature of all points, finding what value of water vapor mixing ratio would be saturation at that temperature, and finding the MSE based on that information. If a parcel of air has a higher MSE than this value, it will be buoyant, thus horizontal distance from the profile is a measure of buoyancy. Note the true buoyancy of a parcel would be relative to its local environment, not an average that includes even the parcel under consideration, but nevertheless the approximation is useful.

Also plotted above is a vertical line at the MSE of the maximum net mass flux, 342.7 K. This will be the "plume" considered to initiate in our entrainment model. If there were no entrainment (and no freezing, but ignore that here as an approximation) a parcel with the initial plume properties would rise with constant MSE of 342.7 K and continue to be buoyant with respect to the h* line until just below 15 km where the lines intersect. Let us consider what would happen if the parcel did mix with an average environment MSE profile, as plotted below.

The Depth of Color

After a short hour meeting this afternoon Steve had an interesting idea about measuring the validity of entrainment rate assumptions (plenty of notes, more to come) and I have a better understanding of a method used in Kuang and Bretherton 2006 (KB06). It came up that the moist static energy (MSE) histograms I have made after KB06 are actually 3D so I thought I'd see if it's easy to make a gif out of different angles using matlab and the free software GIMP, and it was easy!

Do you see color as depth? In the plot below, the colors represent the value of the mass flux occurring at all grid points in the Giga-LES simulation that have a particular MSE at a particular height. The animation below first rotates so you can see that the updraft mass flux (red) has a maximum at low levels, and the downdraft mass flux (blue) is strongest near 3 and 8 km. A further rotation shows another angle, illustrating that the updraft mass flux is occurring for higher values of MSE compared to the downdraft.

The below is a snapshot at 12 hours into the 24 hour simulation, representing the entirety of the mass flux in the volume, over an area almost 42 billion square meters in size filled with hundreds of thousands of simulated clouds.

All of these views can be seen in the original orientation if you can see the depth of color!