Interesting Weather Information

Saturday, August 19, 2017

Here is My Approach to Shooting the Eclipse

What I Want To Photograph

  • Several shots of the eclipse before and after totality.
  • Several near totality shots.
  • The solar corona during totality
  • Using a second camera a time-lapse of the location darkening and brightening into and out of the eclipse

Factors in My Equipment Selection


I will be on location broadcasting live on FOX19 NOW and social media so I cannot manage a large, cumbersome set up. - Light weight equipment, easy t hadle and adjust, no astronomical telescope, a modern DSLR fits the bill.

I will need to broadcast as I shoot. - Maybe handheld shooting - requires fast shutter speed for sharp image and to reduce light to sensor.

When the sun is un-obscured the amount of light is way too bright for a digital DSLR. - Special Filters are needed to reduce the radiation load on the sensor.

As the sun becomes obscured the amount of light decreases dramatically so I will need to adjust the camera sensitivity. I will use the camera in manual mode, change f-stop, or shutter speed or adjust a variable ND filter.

I do not know how large the solar corona will be at totality, so ... I need to use a Zoom Lens

Guiding Principles

  •  I need to reduce the amount of solar radiation reaching the camera sensor. 
  • About half of the sun's light reaching the surface is visible or shorter wavelengths (diagrams below).

  •  
  • I will use a 720nm IR filter - it allows only IR radiation through the lens to the sensor. The R72 filter should reduce the amount of solar radiation reaching the camera sensor by approximately 50%.
  • Transmission curve for Hoya R72 glass. Courtesy: Hoya.com
  • Hoya R72 glass eliminates almost all of the solar radiation with wavelengths shorter than 700nm. There is a transition from 0% to 97% transmission between 700nm and 750nm. Some very long wavelength visible red will leak into the photographs creating a red hue. For my final photos I will adjust color saturation, brightness and contrast in Photoshop. But this drastically reduces the light levels on the camera sensor.
  • All DLSR cameras have a built-in infrared blocking filter which will reduce the amount of  radiation further. Even though the R72 filter has cut the total solar radiation reaching the sensor in half the amount of IR still reaching the sensor could damage the sensor.
  • The combined transmission corves of the IR cut filter and the R72 filter show that what the camera will record is in the grey zone where both allow some solar radiation through.
Typical Canon IR cut filter transmission, Courtesy kolarivision.com

Combined transmission curves of the Canon IR Cut filter and the R72 what gets to the sensor is in the grey zone.

  • To further reduce the amount of radiation reaching the sensor I will use a variable ND filter - this also makes it easy to adjust the settings as the eclipse progresses.

Test Results Saturday 8.19.2017

Canon Mirrorless M3 (Crop Factor 1.66)
Canon Lens EFS 55-250mm Full Zoom (Equivalent Lens Focal Length 415mm)
Canon Mount Adapter EF - EOS M
Manual Focus
Image Stabilization On
1/4000 sec.
F 32
ISO 100
Hoya R-72  720nm IR Filter
Tiffin Variable ND, Set at approximately 4 stops light reduction
Tripod


Contrast increased (100) and brightness decreased (60), color adjusted in Photoshop

200% enlargement of above

Test Results Sunday 8.20.2017

Canon Mirrorless M3 (Crop Factor 1.66)
Canon Lens EFS 55-250mm Full Zoom (Equivalent Lens Focal Length 415mm)
Canon Mount Adapter EF - EOS M
Manual Focus
Image Stabilization On
1/4000 sec.
F 32
ISO 100
Hoya R-72  720nm IR Filter
Tiffin Variable ND, Set at approximately 6 stops light reduction
Tripod
Contrast decreased (60) and brightness decreased (50), no color adjustment, in Photoshop


De-saturated the color, did some noise removal and tweaked brightness and contrast, enlarged.

Final Test


Compare to NASA High Resolution Image in Visible Light




Not bad for prosumer equipment vs. a multi-million dollar imaging system.

Test Results II Sunday 8.20.2017

Canon Mirrorless M Modified to Full Spectrum (IR cut filter removed) (Crop Factor 1.66)
Canon Lens EFS 55-250mm Full Zoom (Equivalent Lens Focal Length 415mm)
Canon Mount Adapter EF - EOS M
Manual Focus
Image Stabilization On
1/4000 sec.
F 22
ISO 100
Hoya U-340 UV Band Pass Filter
Tiffin Variable ND, Set at approximately 4 stops light reduction
Tripod

Hoya U-340 Transmission Curve



  • Hoya U-340 glass transmits virtually no visible light (400nm - 700nm).  
  • This chart is for glass 2.5mm thick. The filter I am using is 2mm thick so I can expect to see some visible light in photos.
  • Spec sheets say that <0.1%, not zero, is transmitted in the visible range by 2.5mm glass.
  • Visible light output from the sun is immense so with a thinner than spec'ed filter and an intense source my camera should record UV, some Visible (skewed to red) and some IR. and yield a creamsicle orange sun before color correction.
  • This set up should decrease visible and IR by 99% and allow through plenty of UV. 







Conclusions


Either set up should work well but using the full spectrum camera with the U-340 filter will mean lower contrast, but less red in the images.

In IR, the first set-up, I will have to be meticulous when focusing manually.

I can reduce the amount of light further by increasing the effect of the variable ND filter up to when the criss-cross pattern appears and reduce reliance on Photoshop.







Tuesday, August 15, 2017

Maysville, KY Area Flash Flooding July 22 - 23, 2017 - Synoptic Analysis

Introduction

During the evening of Saturday July 22, 2017 and the early morning hours of Sunday July 23, 2017 thunderstorms trained roughly along the Ohio River over southern Ohio and northern Kentucky resulting in nearly 8" of rain in approximately a 12 hour period.

Flash flooding claimed one life and there was extensive property and infrastructure damage in the area mostly from Maysville, KY to the northwest into Bracken Co.

The Synoptic Setting


Satellite
During the afternoon of Saturday July 22, 2017 GOES-16  showed a very active convective environment across southern Indiana, southern Ohio and northern Kentucky.  

The GOES 16 Mesoscale Domain Sector (MCD) 1-minute satellite loop below showed multiple outflow boundaries and multiple lines of small convective cells acting to help initiate convection in the region. 

GOES 16 Mesoscale Domain Sector Saturday afternoon July 22, 2017 Courtesy: CIRA, Colorado State University.

Surface
 Surface analysis charts (below) showed a regional-scale convergence zone (solid black line) likely caused by three factors. 
  1. After two days of thunderstorms along and south of the front there were multiple outflow boundary remnants in the region.
  2. Pre-frontal convergence was occurring south of the quasi-stationary front.
  3. The synoptic air flow and terrain were interacting to increase the convergence.

The front, drawn as a cold front on the 00z surface, chart quickly became quasi-stationary as several weak, small lows rippled northeastward along the boundary.

Surface analysis 00z 23Jul2017. Note I used convergence (-divergence) to place boundaries and fronts - not traditional pressure, wind and dew point data. A well defined convergence zone is shown as a black solid line.  See below for the animated gif version, every two hours from 00z to 12z . Plotted with Digital Atmosphere 2015.

Radar
An animated gif radar loop from KILN starting at 00z 23 July 2017 and continuing through 12z July 2017 (8 PM EDT 22nd - 7 AM EDT 23rd) shows thunderstorms training to the southeast and increasing in intensity and coverage as interaction with the surface convergence zone took place.



Winds
From the 925 hPa and 700 hPa 00z streamlines it is obvious that the waves of rain were being steered by the winds at or around 700 hPa. 

In fact northwesterly flow dominated from above 900 hPa upwards past 450 hPa on the 00z KILN sounding steering the convective storms to the southeast.

Plotted and analyzed with Digital Atmosphere 2015

Plotted with RAOB


500 hPa

500 hPa analysis charts (height in geopotential meters, vorticity 10^-5 sec^-1) show a fast-moving shortwave trof moving out of Alberta, heading southeast and weakening across the northern Great Lakes.  In response 500 hPa heights fell across southern Ohio and northern Kentucky. At KILN the heights fell from 5880 m at 00z to 5830 m at 12z 23 JUL 2017. At KBNA the corresponding heights were 5920m and 5890m. The 500 hPa temperature at KILN fell during the same period from -4°C to -8°C. Further investigation will likely reveal the cooling aloft aided in maintaining the heavy rain clusters. The 5880m geopotential height contour highlighted in red to emphasize the height falls. Charts: Courtesy U.S. Taxpayers available at: https://nomads.ncdc.noaa.gov/ncep/NCEP


Rainfall Totals

The highest radar estimated rainfall total (7.96" new algorithm, 6.0" old algorithm) was southwest of Ripley, OH and 5.4 miles northwest of Maysville, KY (as mapped by RadarScope) over rural northwest Mason Co. KY.




Radar totals compared favorably with amounts reported to NWS ILN by observers. 



Even though surface observations were non-existent near where radar indicated the highest rainfall total, at the red "X", approximately 5.4 miles northwest of Maysville, a water rescue and flash flooding reported near Minerva (red circle) increases my confidence that the radar estimates were reliable. In addition a localized radar rainfall maximum of  6.80", is indicated 6.0 miles south-southwest of Maysville (yellow circle)  near where NWS ILN observers  reported 7.42" of rain. Courtesy NWS ILN.




Flooding was extensive and damage to property and infrastructure was extensive in this hilly area with deep, steep-sided creek valleys flowing into the Ohio River. One person was killed when his mobile home was washed into a tree and broke apart.


Convergence at the Surface

Convergence is what happens on an interstate highway as you approach an accident that is blocking part of the roadway. Divergence is what happens when you pass the accident. The same thing happens with flowing air for a variety of reasons.

When air converges at the surface, the air that piles up has only one way to go and that is up.

Convergence/Divergence from Change of Wind Speed
Convergence and divergence in the atmosphere or on the interstate. By: Steve Horstmeyer

On approaching the wreck,  the number of vehicles in a given distance increases - they converge. Once the accident is in your rear-view mirror the vehicles spread out again - they diverge. In the atmosphere is wind speeds decrease down stream convergence will take place unless there is some compensating motion.

Divergence and the flip side of the coin convergence is defined as the percent change in area per unit time. In three dimensions it is the percent change in volume per unit time.


Convergence along a Front/Boundary and Into a  Cyclone
Drawn by: Steve Horstmeyer based on originals by Leung Wai-hung at http://www.hko.gov.hk/education/edu01met/wxphe/ele-condiv-e.htm


Divergence Along a Ridge or Out of an Anticyclone
Drawn by: Steve Horstmeyer based on originals by Leung Wai-hung at http://www.hko.gov.hk/education/edu01met/wxphe/ele-condiv-e.htm


Divergence/Convergence Couplets in 3D Air Motion

Drawn by: Steve Horstmeyer based on originals by Leung Wai-hung at http://www.hko.gov.hk/education/edu01met/wxphe/ele-condiv-e.htm

By convention divergence is positive and convergence is negative. When there is convergence at the surface the only way the air can go is up.

Definition: Divergence/Convergence
Arrows represent surface winds at the corners of an area, originally a square.  As the square moves downwind the winds diverge and the square becomes a rectangle, larger in area than the original. Divergence has taken place. Later the rectangle is transported downwind and the winds now converge. The area of the rectangle decreases. Convergence has taken place. Note more can happen to the square, it can be rotated, lifted and contorted into new shapes. In addition we should really look at convergence and divergence in 3D and compute it for volumes of air. By: Steve Horstmeyer



Trajectories vs. Streamlines and Surface Convergence

Streamlines
Streamlines show a snapshot of the winds, they are an instantaneous view of air flow at a single point in time. Connect the dots to form streamlines and the big picture of air flow at one point in time is visible. The wind at any point is the tangent to the streamline at that point, 

Streamlines do not predict where an air parcel is going unless the weather systems are in a steady-state. That means the systems are stationary, the systems are not decaying or strengthening (i.e. the pressure gradient is not changing) and the systems are not filling or deepening (i.e the central pressure is not changing). This may seem confusing but if a cyclone, for example, grows larger and the central pressure does not change, the pressure gradient decreases.

 If you traverse the map below from Illinois, Missouri and Arkansas to the northeast and east you can see how the horizontal distance between individual streamlines is decreasing.  From Cincinnati eastward along the Ohio River heading eastern Kentucky and West Virginia the streamlines are noticeably closer.

I have added divergence values on the second map and on the third have shaded in the "channel" in which the air is flowing into and through the area that received flash flooding.

The "channel" is confined to the north by the front and to the south by a high pressure system.

Plotted and analyzed with Digital Atmosphere 2015

Plotted and analyzed with Digital Atmosphere 2015

Plotted and analyzed with Digital Atmosphere 2015

Trajectories

A trajectory is the path a parcel of air follows through time. The motion of a parcel of air is the combination of the winds of the weather system, the movement of the system and the change in strength of the system. If a system is in steady state trajectories are the same as streamlines. Trajectories are most often calculated in three dimensions.

The image below shows the trajectories of air originating in northeast Arkansas at 18z 22 July 2017, the afternoon before the flash flooding event in the vicinity of Maysville, KY. 

Note how the trajectories in the NOAA ARL HYSPLIT model are concentrated along the Ohio River. The paths are concentrated there because the air is in effect "channeled" between the front to the north and the anticyclone to the south. Several of the trajectories are spurious in post-event analysis. 

The video below the image uses the same data and goes into additional details.



























video

Surface Maps

On the maps below notice that where you find high pressure the contour value is positive indicating divergence at the surface. Where there is low pressure like the front or the convergence line the value is negative indicating convergence. In addition, areas of surface convergence are areas of rising air.  The greater the convergence the faster the upward motion and the greater the chance thunderstorms will be enhanced.

Because of the three reasons mentioned in the video the surface convergence line (solid black) persisted through the evening of JUL 22 into Sunday morning JUL 23 and was a major player in the flash flooding event.


Plotted and analyzed with Digital Atmosphere 2015



Model Runs: NAM 4K  00z 23 JUL 2017 Run 

Below are cross section diagrams roughly from Jackson, KY (southeast) to Wilmington, OH northwest. The background shading is wind speed and the contours are vertical velocity in microbars/sec.  In pressure coordinates upward motion is negative because pressure decreases upwards.

Translucent shading shows selected areas of upward motion along and near the surface convergence zone highlighted only to draw attention to them.  Typical of high resolution models trying to resolve features near the size of the grid the NAM 4K has trouble pinning down the location of the upward motion.

In addition by 06z it appears convective feedback is beginning to dominate the output because of unrealistic increases in both upward and downward vertical motion.

Even though the high resolution models resolved the vertical motion associated with the surface convergence zone it is unlikely that a forecaster, using that alone, would have predicted  8" of rain in 12 hours.

However using all the available information presented here and watching the system as it developed, flash flooding, given the steep terrain and expected training was a forecast that most experienced meteorologists would have made.

Cross Sections Plotted with RAOB using  NAM 4K Bufkit data archived by Iowa State University.















Monday, August 7, 2017

Welcome to the Hottest Place on Earth

Courtesy: www.nps.gov

When the high temperature is 120° (48.9°C) or hotter 27 times in a two month period, I don't care what anyone claims about "dry heat" - it is brutally hot!

When the air is a searing 129.2° (54°C)  it is kitchen-oven-hot out there. Death Valley heat doesn't feel like the typical sultry Cincinnati summer sauna , as you walk out the door you get smacked by a blast of heat that would make you swear you got your face too close when checking the Thanksgiving turkey.

When it is that hot you do not need an assist from humidity to melt down because you are in the hottest spot on the planet.

Welcome to Death Valley National Park and Reserve, 3 million plus acres of stark reality, a national treasure has the record of the hottest recorded temperature ever on the face of our otherwise, mostly, pleasant planet. On July 10, 1913 the valley was seared by a high air temperature of 134°F (56.7°C), part of a 5-day stretch with high temperatures of 129°F (54°C) or hotter.

If that is not hot enough for you, on July 15, 1972 at Furnace Creek (what a great name!) the temperature of the ground surface reached 201.0°F (93.9°C). That may not be enough heat to liquefy the rubber soles of your shoes but they certainly will get gummy.

The hottest spots on Earth are always deserts. In wetter regions of Earth a great deal of thermal energy is used to evaporate moisture from soils and a rule of thumb meteorologists have is not to predict record high temperatures in summer if soaking rains have fallen the prior week or two.

In addition with scant shading vegetation Earth's surface receives a full frontal assault by an uncountable number of solar photons that can go right to work heating things up because of the lack of moisture in the soil.

If the desert is low, below sea level in much of Death Valley's lowest reaches, it can be even hotter.

Death Valley is dry - very dry.  The average annual rainfall is puny. According to the Western Regional Climate Center at the Desert Research Institute in Reno, NV at Cow Creek Station only 2" falls in an average year. The sandy soil is plenty dry for scorching heat each summer.

The average monthly temperature for July 2017 at Furnace Creek Ranch was 107.24°F (41.8°C), likely the hottest ever measured on Earth.

Park Map and Some Superlative Data


Created by Steve Horstmeyer using Google Earth.


A Hot Summer - Temperature Graphs May, June, July 2017

Note: Data was available in whole degrees only, so there will not be complete agreement with the official final data due to rounding. In addition the average daily temperatures  are calculated using the formula [Tmax + Tmin]/2 = Avg. A more accurate way is to sum the 24 hourly readings and divide by 24. Hourly data was not available.

May 2017 Was Hot in Death Valley
Plotted by: Steve Horstmeyer, Data: GHCN, via https://www.ncdc.noaa.gov/ghcnm/

In June the Heat Was Staggering
Plotted by: Steve Horstmeyer, Data: GHCN, via https://www.ncdc.noaa.gov/ghcnm/

In July it Was Hotter for the Month than in Any Other Place Accurately Measured, EVER!
Plotted by: Steve Horstmeyer, Data: GHCN, via https://www.ncdc.noaa.gov/ghcnm/
Just what can I say about a place that experienced three mornings in July 2017 with low temperatures hotter than 100°F (37.8°C) and 78 days out of 92 with high temperatures 100°F (37.8°C) or hotter and on 27 out of those same 78 days the temperature maxed out at 120°F (48.9°) or hotter?

Death Valley not only feels like the hottest place on Earth, the staggering numbers confirm it.

All Places and All Months on Earth with an 

Average Monthly Temperature 105°F (40.6°C) or Warmer



Data Extracted from : The Global Historical Climatology Network by  Brian Brettschneider.

See his excellent article by Christopher C. Burt, using this data, 
on Death Valley's Record Hottest Month here:




Notice that of the 39 occurrences of a monthly average temperature 105°F (40.6°C) or hotter, 35 occur in the 4 stations (Furnace Creek, Cow Creek, Greenland Ranch, Stovepipe Wells) found in Death Valley.

Christopher  C. Burt in the article linked above makes an excellent case for July 2017 in Death Valley being the hottest reliably measured average monthly temperature on Earth. The observations in Saudi Arabia at King Khaled Military City just do not pass muster.



All dates highlighted in yellow are occurrences NOT during July.

107.44
201408
King Khaled Military City, Saudi Arabia
107.24
201707
Furnace Creek, Death Valley
107.02
200207
Furnace Creek, Death Valley
106.97
200607
Furnace Creek, Death Valley
106.79
191707
Furnace Creek, Death Valley
106.74
192907
Furnace Creek, Death Valley
106.63
200507
Furnace Creek, Death Valley
106.56
193307
Furnace Creek, Death Valley
106.39
200307
Furnace Creek, Death Valley
106.38
195907
Furnace Creek, Death Valley
106.32
195907
Cow Creek
106.32
192707
Greenland Ranch
106.25
191508
Furnace Creek, Death Valley
106.21
195907
Greenland Ranch
106.20
192707
Furnace Creek, Death Valley
106.09
191508
Greenland Ranch
105.91
200707
Furnace Creek, Death Valley
105.71
194207
Greenland Ranch
105.66
192408
Furnace Creek, Death Valley
105.64
201707
Stove Pipe Wells
105.60
200607
Stove Pipe Wells
105.55
201007
Furnace Creek, Death Valley
105.53
199407
Furnace Creek, Death Valley
105.44
201507
King Khaled Military City, Saudi Arabia
105.31
201307
Furnace Creek, Death Valley
105.31
191907
Greenland Ranch
105.30
199808
King Khaled Military City, Saudi Arabia
105.30
195307
Cow Creek
105.30
195307
Greenland Ranch
105.26
199607
Furnace Creek, Death Valley
105.17
194606
Sibi, Pakistan
105.15
201607
Furnace Creek, Death Valley
105.10
196007
Cow Creek
105.10
192107
Furnace Creek, Death Valley
105.10
194207
Furnace Creek, Death Valley
105.10
200807
Furnace Creek, Death Valley
105.10
200907
Furnace Creek, Death Valley
105.04
200507
Stove Pipe Wells
105.01
195207
Cow Creek


Also notice that even though data goes back 106 years to 1911, sixteen of the top 39 occurred in the 18 years since 2000.

The long term average is 39/106 which is one occurrence every 2.7 years. Since the year 2000 16/18 which is one occurrence every 1.13 years. If the data passes quality checks this could be a strong signal of warming,