Hurricane Isaiah on Candlewood Lake

August 4 - 5, 2020

This summer I’ve been doing bi-weekly water quality monitoring in the middle of the lake off my dock on Candlewood Lake in SW Connecticut. As Hurricane Isaiah approached, I thought it would be interesting to measure the lake immediately before and after to see how the storm affected the it.  To that end, I sampled at 8 AM Tuesday as the storm approached, and again at 9 AM on Wednesday after the storm had passed, and compiled the results on this chart.

Not surprisingly, the high, sustained winds mixed up the surface waters.  What was surprising to me was the depth to which that mixing occurred. Surface water temps decreased by almost 2° F, while water deeper down warmed slightly indicating a downward transfer of heat.  Notice also that dissolved oxygen (HDO) shows similar mixing - compare the amount of O2 in the water at 6,7, and 8m before and after the storm - it’s pretty clear that the storm mixing reached a depth of at least 7m (23 feet!!).  Since the storm, BTW, O2 levels in the top 6 meters are back at saturation.
The “bg ppb” column is a measure of blue green algae (cyanobacteria) abundance, and it’s interesting to note how they like to hang out in the colder water this time of year - on 8.14 there were even fewer at the surface, and they were again hanging out in the colder water.  “Sp. cond” stands for specific conductivity, which is a proxy for the salinity of the water, and the numbers we’re recording are at the high end of what we’d like to see. It’s of concern because blue green algae tolerate it better than other plants and animals that normally keep them in check. All fresh water has some salinity, but a likely source of increased salinity in Candlewood are ice melting salts and inorganic fertilizers. Anyway, the influx of fresh rainwater apparently made the lake a tiny bit "fresher".

The Winter Hexagon

(This blog is a rehash of a blog I wrote in December of 2010)

This image is edited from a Stellarium screenshot.  Stellarium is an excellent, free, planetarium program.  Click for a larger view.

As a little boy I was lucky to spend summers under dark skies, and I had parents that helped me learn the constellations and movement of the nighttime skies.  Winter skies, of course, take more effort to observe, but the reward is worth the bundling up.  The "Winter Hexagon" is easy to know, and serves as great guide to the nighttime winter sky.

"Orion's Belt", part of the constellation Orion, is a well known and easily recognized asterism in the northern hemisphere's winter sky (between Betelgeuse and Rigel on the image above).  Six bright stars surround Orion's belt forming the Winter Hexagon, outlined in the image above.  Those stars are easy to find on a dark, clear night - follow the line formed by Orion's Belt down to the left to locate the bright and twinkling star Sirius, drop down perpendicular to the Belt to find blue-white Rigel, follow the line of the belt up to the right to spot Aldebaran (the orange "eye of the bull" in the constellation Taurus).  Look up from Aldebaran to find Capella (in the constellation Auriga), to the left of Capella find Pollux (the brighter of the twins of Gemini), and the sixth star of the hexagon is Procyon, below Pollux on the way back to Sirius. The bright orange star perpendicular to and up from Orion's belt (about as far above the belt as Rigel is below it) is the "red giant" Betelgeuse, the brightest star within the hexagon.

The Moon passes through the Winter Hexagon from right to left (west to east) each month...this month (January, 2019) it will cross the hexagon on the nights of 1/17, 1/18, and 1/19.

June 2013 Solstice and Full Moon

(NOTE: The images below are screenshots from a program called Stellarium, available for free at www.stellarium.org. Click the image for a larger view)

This year (2013), the summer solstice and the June full moon occur within days of each other.  The noon solstice sun (shown in the top image crossing the meridian of my home in western Connecticut with the effects of the atmosphere removed) will have reached its highest point in the sky in 2013.  Note its position on the point of the ecliptic (drawn in red here) that is as far north of the celestial equator (drawn in blue) as can be.  The June 21 sun is in the middle of the ‘winter hexagon’, just above Orion and the star Betelgeuse, and happens to be crossing the plane of the Milky Way galaxy as well.  Venus and Mercury are to the left (east) of the sun, and Jupiter and Mars are just to its right, though none of that will be visible through the sun’s glare.  It’s interesting to note too that the autumnal equinox is just rising due east, and the vernal equinox just setting due west at noon on the summer solstice.

The June full moon, 2 days later, is opposite the sun, occupying the position of the winter solstice at the southernmost point of the ecliptic.  – it will be low in the southern sky all night, following the same path the December sun followed six months ago. And as that full moon crosses your meridian that night, the vernal equinox will be rising in the east as the autumnal equinox sets in the west. The June 23 full moon also happens to be a “perigee full moon” (meaning its slightly eccentric orbit happens to bring it closest to earth on the same day it’s full), and it happens to be the closest perigee of the calendar year, too. While these conditions will make the moon measurably (but not noticeably) bigger, a little brighter, and produce higher than usual high tides, it is nothing extraordinary. You’re likely to see all kinds of “Super Moon” posts in the social media, but keep in mind that perigee full moons occur every 14 months and that this one in particular will not get very high in the sky.

Latest Sunrise of the Year

The latest sunrise of the year will occur on January 5 this year...2 full weeks after the shortest day!  The earliest sunset occurred on December 8 even as the days continued to get shorter and on December 21-22 (the Winter Solstice) we experienced the shortest daylight period of the year. Since then the days have been getting longer, even as the sunrise was getting later.

It might seem as if the latest sunrise and earliest sunset should occur on the shortest day, but both the tilt of the earth's axis and it's slightly elliptical orbit work together to speed and slow the sun relative to our clocks, sometimes pushing the daylight period later into the day (as has been happening in the last month), and other times moving the daylight period into the morning in a predictable pattern we call "the equation of time".

The term solstice means sun stops, or sun stands still.  Of course the sun is always moving east to west across our sky, but from late November through mid January, the sun is nearly as far south as gets (it stops moving further south!) - and that's why we see such uniformity in the length of the day....9 hours 20 minutes on 12/8, 9 hours 13 minutes on the solstice, and 9 hours 20 minutes again on 1/4.  It isn't until late February that you'll really notice rapid lengthening of the day.

Earliest Sunset of the Year

December 8, 2011. For the last few years, I've posted this in early December...12/8 marks the earliest sunset of the year! The daylight period is still getting shorter (people who pay attention to these things know that the shortest day is the Winter Solstice around December 21), but not a lot of people can explain tonight's early sunset.  It turns out that the rate at which the Sun travels across the sky is not constant - the tilt of Earth's axis and its elliptical orbit conspire to push the Sun ahead of our clocks, and then slow it down again, twice every year.  Astronomers call the difference between time told by the Sun (apparent solar time) and clock time (mean solar time) the "equation of time".(If you're interested, you can get the sunrise and sunset times for your location at the US Naval Observatory site.)
The chart on the left above, called the analemma, combines the equation of time with the position of the Sun relative to the equator.  Click it for a larger view, and notice that through most of the fall the Sun has been running ahead of the clock, but in December it began to slow dramatically.
It's the Sun slowing down relative to the clock that's moving the daylight period later into the day even as the days get shorter! The worst of winter is still ahead of us, but at least we'll have a little more evening daylight... (the latest sunrise of the year occurs during the first week of January)
This photo composite was made by Tom Matheson over the course of a year, snapping a picture of the Sun at exactly 8 AM (by the clock) each day.  Here is a labeled image of  Tom's photo.

(This blog is an edited  re-post from December 2009 and 2010)

Cloud Filled Valleys in Pennsylvania

Nearing the end of a red eye flight from California to New York on 10/17/2011, I was treated to this intriguing view of cloud/fog filled valleys as the Sun rose over the northern reaches of the Valley and Ridge Province of Pennsylvania. Overnight temperatures in the valleys had dropped to the dew point and below the stream water temperature. Under those conditions moisture evaporating from the warmer streams quickly condensed to fill the valleys with fog and clouds, some rising high enough to catch light from the rising sun.

The metar above, covering Sunday 10/16/2011 through Monday 10/17/2011 at Williamsport, PA reveals the cool, saturated, and still air that was in place around sunrise on Monday.

The Great Tohoku Quake of March 2011

The day after the great M 9.0 Tohoku quake near Honshu, Japan, on 3/11/2011, CNN ran an article with the headline "Quake moved Japan coast 8 feet, shifted Earth's axis" (it was likely based upon this report out of Caltech the day before). The claim seemed too remarkable to be true, and I wrote to a few seismologist/geologist friends for their take on it. A friend at IRIS sent me to the Geospatial Information Authority of Japan, and I searched around for more emerging information.

It turns out that entire island did not move 8 feet, but near the epicenter the movement and deformations of the island and seafloor were even more astounding than the "8 foot" claim.
I've gathered a number of maps, charts, and images pertinent to the quake and put them in a single Google Earth file available here. The links above, and many more, are in the Google Earth file.
Here are some of the truly incredible things that happened during the quake

• The northeastern shore of the island near the epicenter moved eastward more than 4m during the quake....yes! GPS measurements reveal it! The western part of the island moved eastward by somewhat less than a meter....So part of northern Japan (near the epicenter) is now some 3+m wider than it was prior to the quake! (turn on the japan-slip overlay in the file I sent). I'm assuming that there was significant compressional stress built up in the island, and the land expanded eastward as that stress was released during the quake.
• The motion along the boundary between the subducted Pacific Plate and the overriding Okhotsk Plate* on was on the order of 24m at the epicenter! (turn on the japan-mainshock-slip overlay in the file I sent). Apparently almost all of the motion was accommodated by the overriding plate moving eastward and up, while the Pacific Plate hardly moved. *(The Okhotsk Plate is part of the larger North American Plate).
• The upward movement of the plate raised the level of the seafloor just west of the trench an astounding 4.5+m, and created a basin 2+m deep off the shore (turn on the japan-uplift-and-subsidence overlay in the file I sent). The subsidence of the seafloor lowered the island by about 1m along the shore there (which would have the effect of moving the shoreline inland, but not the rocks under it). I don't know this for a fact, but it seems like a 5m rise in the seafloor and a simultaneous lowering of the coastline would have added signficantly to the damage caused by the tsunami.

And here's something I noticed as I looked over these maps. Bring the japan-mainshock-slip overlay to the top of the 3D display by turning it off, and then on again. The dotted isolines are the depth to the interface between the overriding Okhotsk Plate and the subducted Pacific Plate seafloor.

In the Layers panel in the GE sidebar, expand the Gallery folder and turn on Volcanoes.

Now, notice where the volcanoes are relative to the depth of the plate boundary...Seems like the generation of magma that makes it to the surface begins at about 100km depth..... I drew a profile across the area, and collected data to make the annotated chart above.