Grand View of Fog

Grand View of Fog

Fog streaming in from the pacific as seen from Grand View Park in San Francisco.

(Previously: Post Storm Sunset)

(Related: Golden Gate Park from Grand View Park; TLOTW #7; Post Storm Sunset)

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(Recent Photos)

One Year of Tides Animated (with Sun and Moon)

Updated on Saturday, February 19, 2022

One Year of Tides Animated (with Sun and Moon)

This animation shows a year of tides in San Francisco with the sun and moon:

I was inspired to create this after adding a tide forecast to a personal weather dashboard I have running on an old Surface Pro. I realized I didn't understand tides that much. I still don't, but I know more than I did before.

The animation illustrates four components of the tide. The obvious ones are the position of the sun and moon. When the moon is new or full the Earth, sun and moon are all lined up leading to larger 'spring' tides, which happen twice a month just like spring doesn't. As the moon waxes or wanes and becomes half full the moon and sun are at right angles and partially cancel each other out resulting in lower highs and higher lows. This is the neap tide, almost as unhelpful as 'spring'.

As orbits are not circles the Earth is closer or further away from the sun over the course of a year and the moon behaves the same way. When it's close than usual we get super moons and king tides (finally a type of tide that does what it sounds like). In the animation the sun and moon actually grow and shrink in proportion to their distance from Earth.

Here's how to read the animation. The date and time at the bottom of the screen refers to the tide right in the middle. The full screen shows the forecast running from 12 hours before the current time to 12 hours later. The vertical range is from -4 feet to 10 feet, relative to mean lower low water (MLLW), the average lowest tide over 19 years. The sun and moon are on a different scale - 360 degrees horizontally and 90 degrees vertically.

The tide forecast is pulled from the NOAA Tides and Currents API. I used SunCalc-Net for the position of the sun and moon, and the phase of and distance to the moon. For the distance to the sun I used a formula I found on StackExchange.

I wanted to both fit in a full year and run slowly enough to see what's going on each month so the video is around 20 minutes long. I won't be offended if you don't finish it.

(Related: Summer Solstice 2020; Animation of a year of Global Cloud Cover; Super Flower Blood Moon Eclipse)

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Post Storm Sunset

Updated on Monday, May 10, 2021

Post Storm Sunset

Sunset over the Pacific following a winter storm. Shot from Grand View park in San Francisco.

(Related: Stormy; Grand View of Fog; Sunset #9)

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(Recent Photos)


Updated on Saturday, February 19, 2022


Clouds develop and a storm sweeps in looking west over the Pacific from San Francisco.

(Related: Post Storm Sunset; Sunset #9; Cause and Effect, or Strange Skies over San Francisco)

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(More Timelapses)

San Francisco New Year's Eve Timelapse 2020

Updated on Saturday, February 19, 2022

San Francisco New Year's Eve Timelapse 2020

A timelapse of San Francisco on New Year's Eve 2020:

Shot from Treasure Island, Corona Heights Park. Fort Baker and near Battery 129 in the Marin Headlands. Each sequence was transformed with a style transfer neural network (full details).

(Previously: San Francisco New Year's Eve Timelapse)

(Related: San Francisco New Year's Eve Timelapse; San Francisco Shoreline Timelapse; San Francisco Stars)

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Updated on Saturday, May 8, 2021

I Voted!

I Voted!

This is the first time I have voted by mail. In San Francisco there are clear instructions, a postage paid reply envelope and no need to get your ballot notarized or witnessed or other painful admin. The only real dilemma is the I Voted! sticker. When voting in person you just slap it on and wear it for the rest of the day. But when is the appropriate time for a postal vote? The instructions say:

"Show other San Franciscans you've voted to help encourage them to vote too!"

I get that, but it doesn't really speak to timing.

Is it a November 3rd thing to help with a final turnout push? When you actually fill it out? When you get round to dropping it in a mailbox?

Actually it's even more complex because there is a fancy ballot tracking system. So I get SMS notifications for when USPS has picked up the ballot, when San Francisco County has received it and finally when the ballot is accepted.

I'm just going to wear it today.

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San Francisco November 2020 Ballot Measures

SF 2020

I don't like to vote if I can't string together a rationale that I'm willing to post on my blog, so here are my recommendations for the San Francisco November 2020 ballot measures. It's been a tough year for the city. My neighbors are moving somewhere cheaper and less smoky, I see more houses on the market then usual as I walk around. It's hard to know what the next year will bring and to what extent tech jobs will end up shifting out of the bay area as the giants are forced to match work from home policies and smaller companies follow suit. What's clear to me is that we need to stimulate recovery and stop the city from becoming a worse place to live. And beyond that my ultimate dream of just throwing the politicians out if they're doing a lousy job rather than slogging through ballot measures for them. Until that day, here we go:

A: Health and Homelessness, Parks, and Streets Bond

Yes. The problem with homelessness is only getting worse and the construction will create jobs.

B: Department of Sanitation and Streets, Sanitation and Streets Commission, and Public Works Commission

Yes. The streets are a mess, so anything that shakes up the current system seems like it's worth a try.

C: Removing Citizenship Requirements for Members of City Bodies

Yes. Given the huge number of non-citizens paying taxes and otherwise contributing to the city it makes sense to allow them to participate in civic life. I don't support allowing non-citizens to vote but have no objection to them serving on a commission or other city body.

D: Sheriff Oversight

Yes. I really struggle with American policing. We have SF park rangers, community college police, university police, SFPD, sheriffs, highway patrol and other state police. That's without even starting to think about the various federal TLAs and transportation related agencies. Maybe before defunding the police we should first just spend a few years merging most of them and saving on administrative and uniform design costs? Having said all that I find it very hard to vote against more oversight for a department mainly concerned with running jails that organizes fight clubs at those jails. FFS.

E: Police Staffing

Yes. Doesn't seem to make sense to have a specific number of police officers as a requirement.

F: Business Tax Overhaul

Yes. I've never been in love with the payroll tax and moving to gross receipts with a higher exemption helps small business and startups. Seems like a good trade off.

G: Youth Voting in Local Elections

No. 18 is somewhat arbitrary but it's the point at which you take on adult rights and responsibilities.

H: Neighborhood Commercial Districts and City Permitting

Yes. Makes it faster and easier to permit new businesses and sadly we're going to need a lot of that as we recover.

I: Real Estate Transfer Tax

Yes. We need the revenue even if it is uncertain.

J:  Parcel Tax for San Francisco Unified School District

Yes. More funding for SFUSD. I voted for this before and it's on the ballot again as only a 50% requirement in 2018 instead of a 2/3rds majority.

K: Affordable Housing Authorization

Yes. A step towards creating more affordable housing.

L: Business Tax Based on Comparison of Top Executive's Pay to Employees' Pay

No. I think this is up to each company. Regulate the floor not the ceiling.

RR: Caltrain Sales Tax

Yes. I don't ride Caltrain often but I love it. My dream is coming back from a meeting on the peninsula in a comfortable top deck seat with a couple of cheap canned Gin and Tonics. We need more public transportation and we need it more than ever.

(Related: California November 2020 Propositions; California 2012 Propositions; San Francisco 2012 Propositions)

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Cause and Effect, or Strange Skies over San Francisco

Updated on Saturday, February 19, 2022

Cause and Effect, or Strange Skies over San Francisco

A timelapse combining the mid-August storm and the 'day without a sunrise' on September 9, 2020 in San Francisco (lightning from the storm contributed to the wildfires that blocked the sun).

(Related: San Francisco Stars; Happy Storm; Stormy)

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(More Timelapses)

San Francisco PM2.5

Updated on Monday, August 15, 2022

San Francisco PM2.5

This post is updated hourly with a PM2.5 (2.5 micrometer or smaller particulate matter) map of San Francisco.

The PM2.5 data comes from the Purple Air API. The map uses one hour average readings from outdoor sensors and interpolates each point in San Francisco based on the inverse of the distance to the four closest sensors. The color scale is green to yellow (0-50), yellow to orange (50-100), orange to red (100-150) and red to purple (150-200+). San Francisco is plotted using elevation contours from DataSF.

Updated 2022-06-11 12:28:

The map is currently broken. The URL I use to download sensor data started returning a 500 error code at the end of may (Error: Server Error / The server encountered an error and could not complete your request. Please try again in 30 seconds.). This seemed like something Purple would need to fix. On closer inspection the error occurs after a redirect to which sounds like too many requests (a 4xx error surely). With even more digging it turns out the download link is no longer supported (410 maybe then?) and so I'll need to migrate to the REST API to get this working again. I'm currently trying to get an API key and will get this fixed as soon as I can.

Updated 2022-06-13 17:28:

Purple Air were kind enough to issue me with an API key so the map is back to updating hourly.

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