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Boeing 787 Reaches 801 MPH as a Jet Stream Packs Record-Breaking Speeds

latimes.com

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Re: Boeing 787 Reaches 801 MPH as a Jet Stream Packs Record-Breaking Speeds

#161

Post by cr1895 »

yesenadam wrote: post #150
bartread wrote: post #95

Earlier quoted context omitted.

> Wind is "named" after where it comes from. This is absolutely true, but has always infuriated me because it seems needlessly contrary as compared to the way we speak about anything else travelling in a direction as read from a compass. Does anybody know why it's the case?

Can you name anything else named after where it's going, not where it comes from? I can't think of anything named like that, but I guess there must be some.

Within a marine context, current is typically given as direction to while wind and waves are direction from.

Re: Boeing 787 Reaches 801 MPH as a Jet Stream Packs Record-Breaking Speeds

#162

Post by Symbiote »

photojosh wrote: post #115
bamboozled wrote: post #97

Earlier quoted context omitted.

You’re right I did just paste that figure from Google conversions. Using the metric system over the imperial system isn’t being pedantic, it’s just courtesy in 2019

It's from a USA-based newspaper. I hate imperial with a passion, but it is still their backarsed standard. Surely anyone with a scientific bent can do a rough calculation in their head. For me, it was "oh, around 1300 km/h, cool" and moved on...

In many countries, miles are as obscure to people as leagues, perches and gills probably are to you.

In others, the word refers to a significantly different measure. For example, Norwegian and Swedish people often use the word to mean 10km, and can misunderstand a phrase like "it's just five miles outside London".

There's a list of possibilities here: https://en.wikipedia.org/wiki/Mile

Re: Boeing 787 Reaches 801 MPH as a Jet Stream Packs Record-Breaking Speeds

#163

Post by ringshall »

wefarrell wrote: post #160
e40 wrote: post #104

Earlier quoted context omitted.

Do you know if the rides in higher energy jet streams are less comfortable, or is it undetectable by the passengers?

It would be as undetectable as the motion of the earth. It's the change in velocity (not the velocity itself) that causes you to feel something. Moving from one air current to another, with a large change in velocity, would be very noticeable.

They could be more turbulent. I presume they aren’t, though.

Re: Boeing 787 Reaches 801 MPH as a Jet Stream Packs Record-Breaking Speeds

#164

Post by reacweb »

rconti wrote: post #42
abakker wrote: post #20

This makes me think that some time in the distant future, when we're really great a terraforming, we could influence the weather of the planet specifically to create functional jet streams that we could use to make travel faster, and then plan air routes specifically to use them. A more serious question: I assume this kind of event doesn't actually save fuel because the airplane still has to maintain the same airspee…

No, it saves fuel. They're probably going faster AND using less throttle. Cruise speed is WAY above stall speed.

No. When you are flying high (at the route flight level), air becomes less dense and the stall speed increases a lot (expressed in true air speed). When a flight is at its highest available flight level, the range of available speeds is very narrow.

Re: Boeing 787 Reaches 801 MPH as a Jet Stream Packs Record-Breaking Speeds

#165

Post by staticautomatic »

Stratoscope wrote: post #147
TheLoneAdmin wrote: post #18

Earlier quoted context omitted.

The radius of the earth + 30,000 ft is about 0.14% more than just the radius of the earth. Basically ignore it, unless you are programming guidance control systems.

This reminds me of a math puzzle I read many years ago. It went something like this: "Assume the Earth is a perfect sphere, and its circumference is 25,000 miles. You have a 25,000 mile long rope looped all the way around the Equator, so it is tight against the surface. Now you want to raise the rope one foot in the air, all the way around. How much more rope do you need?" I thought about this and said, "You need a l…

I had a science test in high school with a question that involved something to do with calculating the air pressure inside an airplane at some high altitude. I went up to to the teacher and said "is this a trick question? Airplanes are pressurized at that altitude" He looked around the room nervously and then told me to assume the airplane wasn't pressurized.

Re: Boeing 787 Reaches 801 MPH as a Jet Stream Packs Record-Breaking Speeds

#166

Post by bartread »

yesenadam wrote: post #150
bartread wrote: post #95

Earlier quoted context omitted.

> Wind is "named" after where it comes from. This is absolutely true, but has always infuriated me because it seems needlessly contrary as compared to the way we speak about anything else travelling in a direction as read from a compass. Does anybody know why it's the case?

Can you name anything else named after where it's going, not where it comes from? I can't think of anything named like that, but I guess there must be some.

Or when you're out walking you might say that you're "heading north". Granted if you wanted to report your rough position relative to someone else you might say something like, "I'm 500m north of you."

Re: Boeing 787 Reaches 801 MPH as a Jet Stream Packs Record-Breaking Speeds

#167

Post by bartread »

ahartmetz wrote: post #116
bartread wrote: post #95

Earlier quoted context omitted.

> Wind is "named" after where it comes from. This is absolutely true, but has always infuriated me because it seems needlessly contrary as compared to the way we speak about anything else travelling in a direction as read from a compass. Does anybody know why it's the case?

Probably because it matters where the air was before. Stuff like: north wind is could, south wind is warm, west wind is humid, etc

Doesn't that very much depend on where you are though? E.g., with respect to the equator, major bodies of water and landmasses, mountain ranges, prevailing weather conditions. Also perhaps on seasons.

I can understand that it might be just an ancient tradition originating from a particular part of the world, that we've turned into a convention, but it loses meaning when you go elsewhere.

Re: Boeing 787 Reaches 801 MPH as a Jet Stream Packs Record-Breaking Speeds

#168

Post by Stratoscope »

staticautomatic wrote: post #165
Stratoscope wrote: post #147

Earlier quoted context omitted.

This reminds me of a math puzzle I read many years ago. It went something like this: "Assume the Earth is a perfect sphere, and its circumference is 25,000 miles. You have a 25,000 mile long rope looped all the way around the Equator, so it is tight against the surface. Now you want to raise the rope one foot in the air, all the way around. How much more rope do you need?" I thought about this and said, "You need a l…

I had a science test in high school with a question that involved something to do with calculating the air pressure inside an airplane at some high altitude. I went up to to the teacher and said "is this a trick question? Airplanes are pressurized at that altitude" He looked around the room nervously and then told me to assume the airplane wasn't pressurized.

Ah yes, the notorious spherical cow!

https://en.wikipedia.org/wiki/Spherical_cow

Re: Boeing 787 Reaches 801 MPH as a Jet Stream Packs Record-Breaking Speeds

#169

Post by yread »

gHosts wrote: post #124
kawfey wrote: post #75

An incredible visualization of winds aloft (and several other parameters can be seen at https://earth.nullschool.net/ . Currently the jetstream (i.e. winds at 250 hPa altitude) are hitting around 230mph (360km/h).

When I first heard about global warming, the physicist in me said, hmm, the major effect of this will be energetic weather systems will become more energetic. Now put that together with my personal experience of extreme weather events both in NZ and ZA, the jet streams has _always_ been involved. http://squall.sfsu.edu/scripts/shemjetstream_model.html ie. If I see a major stream coming near me... Big Stuff happens wi…

Apparently, climate change brings more irregularities to the jet stream

https://insideclimatenews.org/news/31102018/jet-stream-clima...

Re: Boeing 787 Reaches 801 MPH as a Jet Stream Packs Record-Breaking Speeds

#170

Post by heavenlyblue »

snowwrestler wrote: post #105
heavenlyblue wrote: post #78

Earlier quoted context omitted.

>> GPS measurements are comprised of a 2D surface coordinate system GPS is inherently 3 dimensional.

> and an altitude above mean sea level

Nah, you're clearly misunderstanding how GPS works.

GPS allows you to directly measure displacement of any 2 points in 3 dimensions.

You're speaking of the altitude + lat/lon instead, which is in polar coordinates.

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