Cell Phones on Airplanes

It's against FCC regulations to use a cell phone on an airplane.   Most people seem to think the reason is that they're afraid it'll interfere with the navigation of the airplane.   Here's the FCC's policy statement on the subject.  Note in particular the second statement: they're worried about interference with the ground.

To understand this, it's important to understand how a cell phone works.  Each phone has a radio transmitter/receiver, aka transceiver. It's capable of being tuned to any one of (depending on protocol) dozens or hundreds of channels.  Whether it's digital or analog, 3G, 4G, TDM, packet, etc., what exactly constitutes a channel is immaterial to the issue.  What's important is that there are a limited number of them.

The ground part of this consists of a network of transceivers mounted on poles or other high places, called cell towers,  which can tune to the same channels.  They are organized into cells, which is a region on the ground using wires or microwave links to connect to each other and the rest of the phone system.  Each cell tower can use, at most, the number of channels in the protocol.  Phones are low power radios and they actually reduce power so that they can't be heard by more than one or two cell towers at once. Because any bandwidth a phone uses must be reserved by every cell tower that can receive the signal.  (this is not strictly true--there's some collision recovery in several of the digital protocols--but collisions reduce bandwidth, so the essential problem remains.  for simplicity, let's pretend it's all channels and ignore packets and collisions and such)

Most of the time, most phones are not in use--they have a handshake with their local tower so the system knows which phone to ring, but this doesn't take much bandwidth.  Phones that are in use use a lot of bandwidth.  If an area has a lot of phone traffic--a big building for example, they'll put extra towers in to adapt.

But it's important to recognize the two dimensional design of the network.  Most of the time you're fairly close to the center of a cell.  you use two cells only when you're near the border of both.  But if you're up in the sky, you're a lot farther from the closest cell, and the second closest might be only a little farther yet.  Worse, there might be several others that are still close enough that any bandwidth you use on your phone must be reserved for all the cells.  In a dense city and a plane at 10,000 feet, this could be a hundred cells or more.

Now imagine that a plane is flying over our group of cells, carrying 100 passengers who simultaneously want to call their spouse or client or whatever, telling them the plane is about to land, time to come pick me up at the airport.  They've used 100 channels in every cell within range--which could be a band 10 or 15 miles wide and 50 miles long, under the landing pattern, which is usually in a big city.  Not only that, there's another plane coming along a minute or two later doing the same thing, with an effect that's overlapping the first plane.  Two or three such planes could exceed the entire capacity of the entire group of cells.

So they ban it.  If one or two people call, it's no big deal; it's stealing those two channels from all those cells, but they have enough capacity they can handle it.  If half of them leave their phones in ground mode by mistake, there's so little bandwidth used it hardly matters.  It's only if a lot of them are using a lot of bandwidth simultaneously that it's a problem.  Adding more cell towers doesn't solve it: they'd be in range too. what does solve it is a cell repeater on the airplane, which uses a different protocol to talk to the ground.  FCC is happy to have people think it'll cause interference with the airplane they're on, because that'll keep them from cheating.

Similarly, the flight attendants don't have the time to figure out which electronic device might cause ground interference and which is harmless.    The fact is that most are harmless, although there is a tiny chance that one of them might cause a bunch of RFI, and a real problem, either because it's non FCC compliant or because it's malfunctioning.  The one they don't recognize might be the one that causes the problem.  Simpler and safer to have a single rule and ban them all.

Rainbows and Green Flashes

I've seen the "green flash" three times--all at sunset, from west coast beaches:  Once from Cannon Beach, in Oregon, Twice from Pajaro Dunes, in California, all in the winter.  There's a reason for this, as I'll get into later.  Many people are skeptical that it's a real thing.  It is, but things have to line up just exactly right to be able to see it:

You need to have clear viewing all the way to the horizon and past it--no clouds, no haze, especially no mountains.  Typically these conditions happen only when it's been raining and it's cleared up just an hour or two before sunset.  it helps if there's a little bit of haze right at the horizon, but not much.

The water needs to be warmer than the air.  This is why it tends to be a winter phenomenon.  The green flash is a member of the broad class of optical phenomena called "mirage", which results from layers of air being heated differently, resulting in them refracting different colors differently.  The bottom level of air needs to be quite a bit warmer than the air at eye level, which really can only happen if it's being heated by water.  Because blue and green are scattered more than red, sunsets tend to look red.  But there's a moment that the red light is all passing above your eye while green is coming your way.

The reason I think rainbows are similar is because they take a combination of several things to make them happen:  it needs to be clear enough that the water vapor is well lit.  But rainbows aren't very bright and it's hard to see them against a clear blue sky: there needs to be something behind.  it's usually in front of clouds or something else that's darker than the sky.  The primary rainbow is about 2 degrees thick and it's about 80 to 84 degrees wide.  Rainbows are the result different colors of light being refracted differently by water, but all being reflected together inside drops of water.   (To see all of it with a 35mm camera, you need a 19mm lens.  usually you can't see all of it.  to see all of a double rainbow, you need a 13mm lens.)

My favorite rainbow was when I was driving almost due north late on a winter afternoon.  I was at the southern edge of a storm--behind me was well lit, but the hood of my car was in light rain.  the rainbow appeared to be around the hood of my car.  Todd Newman was with me and we both saw it, but we didn't have a camera convenient and it didn't last long.

Bay States

When I moved to Massachusetts from the San Francisco Bay area, I thought it was funny that Massachusetts was the Bay State, while California, which has many more bays, is not.

A Bay is a broad inlet of the sea where the land curves inward.  This could be quite a shallow inlet, or a deep one.  Some bays are called harbors when they're confined enough to provide some protection.  A sound is between two bodies and is open at both ends.

Here's a list of the Bay States:
Maine:  The biggest is Penobscot Bay, but there are zillions of others.
New Hampshire, with a very short coastline, nevertheless has a number of bays.
Massachusetts has three main bays: Massachusetts Bay, Cape Cod Bay, and Buzzards bay.  there are also a number of smaller bays and sounds.
Rhode Island is basically one big Bay: Narragansett Bay, with a bunch of penninsulas and islands in it.
Connecticut has many things that would be called bays, but most of them seem to be unnamed, or are called harbors.
New York has many bays: New York Bay, Jamaica Bay, several more, even not counting most of NY's shoreline on Long Island.
New Jersey: Sandy Hook Bay, Newark Bay, Delaware Bay, many others.
Delaware is largely defined by it's giant bay, which is the boundary between it and New Jersey.
Maryland is similarly defined by its giant bay, the Chesapeake, which continues on to Virginia
Virginia's Atlantic Seaboard is largely the Chesapeake bay, although there's a short section that has a few bays of its own, and there's an isolated part of Virginia on the Delaware penninsula.
North and South Carolina's Coastline consists of a series of large, wide bays.
The coastal area of Georgia is made up of a bunch of low islands.  Consequently, most of their inlets are sounds, not bays.
Florida has many famous bays: Tampa Bay, Biscayne Bay, Pensacola Bay, many others.
Alabama is a very short coastline, but it's basically all Bays.  Mobile Bay is the biggest.
Mississippi also has a short coastline: Pascagoula Bay, Biloxi Bay, St Louis Bay are all on it.
The Mississippi Delta area of Louisiana has so many bays it's silly to try to count.  I gave it a start and realized I was making mistakes around the time I got to 100.
Texas has quite a few too: Galveston Bay, Corpus Christi Bay, etc.
California starts at the south with San Diego Bay, Mission Bay, Alamitos Bay, Morro Bay, Monterey Bay, San Francisco Bay, Drakes Bay, Tomales Bay, Humbolt Bay.  Lots more.
Oregon: Coos Bay, Alsea Bay, Tillamook Bay, Youngs Bay.  Small Bays.
Washington: Willapa Bay, Grays Harbor, Discovery Bay, Puget Sound (which is really a bay with some big islands in it)

I won't try to do Alaska and Hawaii.

My ranking is based on how big a part of the state the bay or bays are:
#1 Rhode Island
#2 Delaware
#3: Maryland
#4: Massachusetts
#5 California
#6 Florida

If California didn't also have a bunch of big mountains and valleys, it'd be #1.