Some nerds go on a hike

along the mesa trail after being kicked out of the computer lab at NCAR's Mesa Lab (aka the Sleeper building).

Unlike the previous days, there were no afternoon thunderstorms and the mid-afternoon heat and altitude were challenging.

Nerd 1: (Looks at watch.  4:45 PM)  What do you think?  600 watts per square meter?

Nerd 2: (Looks at sky.)  Given the altitude, perhaps 650.

Nerd 2 works at the Department of Energy's Atmospheric Radiation Measurement (ARM) Program Southern Great Plains (SGP) Central Facility, Oklahoma so she looks at solar irradiance data for a living. Nerd 1 has no excuse other than being a nerd.

A quick search yielded a compendium of solar irradiance data servers put together by NREL.  Following the link to National Wind Technology Center, enter in the day of the hike and voila.  Click to make the graph below bigger and you will note that, taking into effect daylight savings time and averaging over the noise of passing clouds, Nerd 2 was spot on!

Check out the solar irradiance back at the beach on an exceptionally sunny and cloud-free day.

BTW, solar irradiance is a measure of the amount of light energy per unit area from the sun, integrated over all light frequencies.  See the solar spectrum and images of the sun at different frequencies, including the UV and X-rays.  Fortunately, the ozone layer screens out much of the UV so we don't fry here on the surface.

If you want to see how much power you can generate with photovoltaic cells on your house, take a look at the climatology of solar irradiance near you and multiply by the efficiency factor for the type of panel (a number much less than 1 or 100% efficiency).  Does the sun generally shine when you need to draw power?

The reliability and availability of solar power deserves it's own post.  Later.

Two nerds drive up a mountain pass...

The minivan gives the outside temperature.
The GPS unit gives the altitude.

She: Our lapse rate is slower than the saturated adiabatic lapse rate.

He: That's because we are driving into a storm front.

She: Isn't that what I just said?

Bystander in the backseat: Huh?

Background: If a parcel of dry air is lifted adiabatically (without exchanging heat with its surroundings), then the temperature cools off 9.8 degrees Celsius per 1000 meters altitude.  If the air is saturated, it cools off more slowly,  about 5 degrees C per 1000 meters.

Traveling between Durango and Silverton, along the Million Dollar Highway, our elevation went up by over 3000 feet or about a 1000 meters, but the temperature only changed about 3 degrees C.

That very low lapse rate implied that we had crossed the boundary between two distinct air parcels--what is commonly called a front.  It might have also implied that we got caught in the upslope of a diurnal mountain-valley circulation, but it was the opposite of the type of calm and sunny day that sets up that type of wind pattern.  It was cloudy and cold.  When two air masses collide, a violent storm can erupt.

Sure enough, it started to rain as we crested the pass, gradually becoming heavier and there were even a small amount of hail.  What a great day for a picnic!  ;-)

On that day, it did NOT look like this picture from Wikipedia commons, but it was beautiful nonetheless.

No more bubbles! (of the bad kind)

There was an internet rant about sewing tutorials written by hipsters who learned how to sew 10 minutes ago that promulgate very bad techniques.  I stayed out of the fray, but nodded my head in agreement.  Some of those blogs give information that is just flat out wrong.  The best sewing advice I have seen have usually come from women who have sewn for decades and are not as photogenic and thin as the hipsters with their beautifully-styled blogs. 

One of the best sewing tutorials sites is run by Pam Erny, proprietress of Fashion Sewing Supply.  Her recent tutorial on how to make two exactly identical shirt pockets was fantastic.  I emailed her right away to ask if there was a way for me to send a micropayment to her for the sewing lesson.  She said that was not necessary, but she would appreciate if I spread the word about her business.

If you read sewing blogs of experienced seamsters, you may notice that many most of us purchase interfacing and notions from FSS.  To save on shipping, I put in an order every year or so, whenever I run low.

Actually, I don't recommend .ever. using fusible interfacing from big box sewing/craft stores.   The Pellon stuff will bubble eventually, ruining all of your hard work.  The Handler Textiles interfacing from independent fabric stores is slightly better, though it's a drag to wash and rewash the stuff to shrink it before application.

But, if you really want your work to hold up, wash after wash, and you don't want the hassle of prewashing your interfacing, you need to use the stuff Pam sells at FSS.  It's preshrunk, before the adhesive is sprayed on the back.  That means, the interfacing won't shrink when you iron it on your fashion fabric, causing the dreaded bubbling.  Moreover, the adhesive is applied evenly and thinly; no dots of adhesive that show through here.

I have no affiliation with FSS except that I am a satisfied customer and I am not paid for this plug.  But, I would like to point out that Pam is having a huge sale right now to celebrate her 7th year in business.

The sale runs through August 15 so take stock of what you need soon and place your order. She often runs out of some type of interfacing I want during her sales. But, last time, she held off shipping my order until she was able to restock, so I only had to pay for shipping for one package. Her shipping rates are reasonable; she charges only what it actually costs her (unlike other places!).