Friday, September 26, 2014

San Diego: Regents Bridge Over Rose Canyon Is Dead

Ding dong, hurrah! A number of people and organizations have fought this over the years. Thanks for preserving the canyon. Now everyone else, get out there and kill some fennel!

Thursday, September 25, 2014

To What Extent Does Minutes of Sunlight Explain Temperature?

The list of stupid things I wonder about grows longer still. As I evolved in my complaining about Sacramento's summer weather, I started thinking about to what degree you can predict the daily temperature from the minutes of sunlight. Obviously the relationship can't be 1:1 because the solstices are not the coldest or hottest days on average. But it turns out, for American cities that don't have marine climates, minutes of sunlight accounts for over 70% of the variation in average daily temperatures. You might say, "Of course! What else did you think explained hot summers and cold winters, seasonal volcanism?" It's that I didn't expect the relationship to be so clear, and to be obscured by other climactic factors.

Below please note sunlight-temperature scatter plots for Phoenix, Sacramento, San Diego, and Philadelphia. Initially I expected Sacramento and Phoenix to be similar, and San Diego and Philadelphia (Philadelphia because of humidity and cloud cover). I also didn't expect too tight of a correlation. Temperature data is from 1980-2012.

This was a surprise. Cloud cover and humidity per se don't make a difference, but being downwind from a massive heat sink does. And when you break the temperature cycle in half, and do a separate linear goodness of fit for both decreasing and increasing temperature, the R^2 goes up past 0.9! (Again, for the non-marine cities.)

I even adjusted Sacramento for the differing angle of the sunlight (i.e. a minute of sunlight in January is different than in May, because the sun is lower, and the same power is therefore spread over a greater area; that is to say, watts per square meter is lower in winter than summer.) After all, every place on Earth gets the same minutes of daylight per year, but obviously the higher the latitude, the greater the departure from directly-overhead sunlight, and therefore the less power being delivered, and obviously for this reason higher latitudes are colder. But it turns out that adjusting for incident intensity comes out in the wash, within the same dataset - adjusting for different sun intensity only increased the goodness of fit by about 0.02. There is an obvious difference in the pointiness of winter (Sac and PHX are pointier than Philly, i.e. they start warming after the solstice more rapidly than Philly); this might be explained by difference in cloud cover.

One take home: if you want to identify marine-influenced climates, you could write a program that calculates the R^2 for any city, given latitude (so you can calculate minutes of sunlight each day) and daily average temperature data. The worse the fit, the more there's a massive heat sink nearby screwing up your prediction, i.e. the more marine-influenced is the climate you're looking at.

ADDED LATER: This very nice related NOAA map I found at the Map Porn subreddit. Purpler = sooner (December), green-yellow = later (February).

Temperature data is from average daily temperature archive, University of Dayton.

Wednesday, September 24, 2014

From Rattlesnake Bar to Auburn - It's Autumn

I am always happy to have underestimated the neato-ness of a trail. I initially thought "Ih, dry oak scrub at the start of the foothills, whatever..." I was running it to connect the American River Trail to Western States in my little projecty. And boy was I wrong. Turkeys everywhere, a beautiful little pond, a rushing mountain stream, wild grapes, deer and elk everywhere, an old flume alongside the trail, and this critter, out for his autumnal walk. Other pictures follow below.

Forgive me the video's shakiness, my priority was first not having a tarantula on me, and second entertaining you, dear blog reader.

These pictures are along the North Fork of the American River, just upstream of where it runs into Lake Folsom. The first two pictures below are wild grapes near Mormon Ravine. They do in fact taste like grapes.

Monday, September 22, 2014

Tuesday, September 16, 2014

Minarets and Bristlecones

This weekend we wanted to get out of Doge* so we went over those mountains over there, and screwed around on the east side. We got up in them Minarets (which included seeing the Devil's Postpile, finally; also see here) and seeing the Bristlecone Forest, finally. Below please see Minarets. Was warm even at 10,000'.

Simple question for geology and materials science types: if basalt sometimes forms regular hexagons (as with Devil's Postpile) because it's a stable shape, and salt flats do the same thing, why don't they always (or usually) form these shapes? Why are the regular hexagonal patterns so rare as to stick out to us?

Below, seen in Bishop: I know I'm often frustrated by gelato shops that don't sell weapons when I need one. (Or the other way around.) Finally! A store that addresses this problem! However, steak was consumed at the best steakhouse in town, which is in (no kidding) the local bowling alley, and which is (similar lack of kidding) a solid place for a steak and a beer.

Above: I said we wanted to get out of Doge, and I meant it.
Below: Cooking Wiss a Doge.

The next day we saw us some 4,000 year old trees. The 4.5 mile trail from the visitor center in the Bristlecone Forest may not seem like much but the flora changes based on north- or south-facing slopes and elevation are pretty interesting. Fun trail. Plus my car turned 100,000 on the way; can't think of a better place to mark the occasion. Panorama is taken on the high road between the visitor center and the UC research station.