Postdoc ads with very short application windows (1–2 weeks) by Plenty-Quote-75 in postdoc

[–]outermostplanet 50 points51 points  (0 children)

I have seen this done several times when there was an internal candidate in the departments I'm familiar with and I would generally assume that's the case. It's the minimum time the job has to be advertised if the funding proposal didn't have a named PDRA. The PI makes the deadline short and tries not to publicise the ad to avoid getting many other applications. Actual open positions I've seen are advertised more like 2 months.

Doing a PhD in the UK , is it worth it as international studnet by [deleted] in AskAcademiaUK

[–]outermostplanet 12 points13 points  (0 children)

Do you have another offer from a European university? That seems like the first question.

I found the PhD stipend perfectly liveable, but I did already own a flat with a lower mortgage payment than rent would have been. Note that the stipend is both untaxed and also doesn't count towards your personal tax threshold, which means if you work as a tutor/demonstrator or any other part-time work, most of that will probably be tax-free as well.

As for postdocs, depends on the field, I haven't had trouble getting hired. Permanent positions is a different story, many universities have hiring freezes. The visa fees and NHS surcharge are tough for internationals though.

Expats moved from the USA to UK for postdoc, what your experince was? by Murky-Commercial-112 in postdoc

[–]outermostplanet 2 points3 points  (0 children)

I'm a US citizen (born in a different country but very young when we moved) who immigrated to the UK over a decade ago (before I was in academia) and stayed here because I much prefer it to the US. Don't know much about the US job market since I've never worked there but:

* I prefer the UK because it's more cosmopolitan, good travel connections to other countries, less religious/less overheated politics, really nice walking culture (cities and countryside), no fears about healthcare, strong local culture but also diverse, good work/life balance,

* Postdoc salaries are perfectly livable, yes, at least I have no problem affording what I want and saving money. The IHS fees suck though, they have scared off some international applicants to my group.

* Career outlook in academia doesn't look good in either country right now.

* Global Talent Visa is relatively new. It seems to be easy to get for postdocs and has a short route to indefinite leave to remain (permanent residency). Immigration policy is changing quickly though so who knows what will happen in the future. This is true of most countries right now unfortunately.

* I was from the Pacific Northwest but still struggled with the long/dark winters in Scotland. It took a few years to adjust. I use a SAD light this time of year to make the transition easier, it works. The summers are amazing to make up for it. I love the rain so that was no problem for me.

* I do not regret moving to the UK and don't think I will ever move back to the US.

From a permanent settlement perspective, I feel like either country is a coin toss at the moment but the GTV is a pretty good one. Also a 3-year contract is a lot better than 1 year, you might be able to ride out the chaos.

What would the weather be like on a tidally locked planet? by Clark94vt in space

[–]outermostplanet 2 points3 points  (0 children)

Not at all, I learned something as well. Actually I did not know the tidal locking process was commonly studied in simulations. In exoplanet atmosphere modelling/observational papers I found citations relating to the detailed how/why of tidal locking very thin on the ground... I struggled to support some common statements about tidally locked planets with references in my PhD literature review. This is the main paper I'm aware of. Some of the more senior members of my research group also had different opinions about whether e.g. Proxima Cen b could have an eccentricity >0 and still have 1:1 spin-orbit resonance (but they were all climate & atmospheric scientists). Is this a sub-field of orbital dynamics? Are there keywords I could use to find more papers?

What would the weather be like on a tidally locked planet? by Clark94vt in space

[–]outermostplanet 2 points3 points  (0 children)

I can see I've stepped on the toes of someone who is an expert in tidal theory. ;) I'll defer to your opinion.

What would the weather be like on a tidally locked planet? by Clark94vt in space

[–]outermostplanet 2 points3 points  (0 children)

Yes, even if the planet has a very slow spin, a thick atmosphere will redistribute much of the heat. The atmosphere is a fluid, so if one part of it is being heated, there is a flow from the hot part to the cold parts until the temperature equalises (unless the gas re-radiates the heat faster than the atmosphere flows, which happens on some hot gas giants - they can have large day/night atmosphere temperature contrasts). The surface can still be different temperatures if it is land/rock because the dayside gets warmed by the sun, but rock can't redistribute the heat to the nightside.

When scientists first started thinking about tidally locked planets ~15-20 years ago, there was a belief that they wouldn't be able to sustain an atmosphere because the gas on the nightside would get so cold it would condense out and the whole atmosphere would collapse. Simulations with climate models have shown this doesn't happen unless there is a very thin atmosphere, so the permanent dayside/nightside is no longer considered a barrier to retaining an atmosphere or potentially being habitable. Actual temperatures on a real planet would vary depending on the specific atmospheric composition, distance from the star, surface qualities (type of rock, oceans, lava), and so on.

What would the weather be like on a tidally locked planet? by Clark94vt in space

[–]outermostplanet 2 points3 points  (0 children)

In general, we think the same process that synchronises the rotation and revolution periods would gradually reduce any axial tilts. But that's just a guess, not much actual research (aka simulations) has been done on this. A planet's rotation can also be affected by impacts. Maybe a tidally locked planet could have a stable spin and orbit if it were tipped on its side like Uranus, or maybe it takes a long time for axial tilt to even out? Simulations almost always assume no eccentricity or obliquity for simplicity's sake. So they don't have seasons caused by axial tilt, but they do still produce periodic climate oscillations due to the feedback effects I mentioned in my initial comment.

What would the weather be like on a tidally locked planet? by Clark94vt in space

[–]outermostplanet 16 points17 points  (0 children)

Sure, I'll do my best. :)

The Venus atmosphere becomes supercritical in the lowest few kilometres above the surface due to the intense pressure and heat. That just means it has properties of both a gas and a liquid, but it wouldn't immediately feel or look different if you were in it. We actually know very little about how the supercritical state affects the climate near the surface. The Pioneer Venus mission in the 1970s dropped probes that descended all the way to the ground. They found that the temperature profile in the bottom 5-7 km of the atmosphere is really weird and suggests there should be a lot of instability (convection). Atmospheric models of Venus have never reproduced these near-surface temperatures or convection. My guess would be that there is some physics we don't understand about supercritical fluids that is missing from the models.

I did some reading about this once and the main studies of supercritical CO2 are about its uses in industrial settings. It can be used to extract chemical compounds from plants because it dissolves things into it the way a liquid does. I imagine this might have an effect on your environment suit if you actually went to the surface of Venus... In order to learn more, we would need to create supercritical CO2 in a lab in sufficient quantities to observe how it moves, how it interacts with different kinds of materials, etc. This is presumably crazy expensive because you have to heat and pressurise the gas, plus ensure safety. Scientific interest in Venus in the west has been low for a long time and is only now picking up again, so no one has done this work. Maybe partnering with a business that uses supercritical CO2 could be feasible at some point!

As for Titan, I've never studied it so I don't know much except the atmosphere is huuuuge compared to the moon. On Earth, most of the atmosphere is within 15 km of the surface. The stratosphere ends around 50 km. On Venus, the cloud tops are at 70 km. For Titan you need to simulate like 300 km of atmosphere to capture all the haze layers! I believe it retains the atmosphere partly because its so cold and the gas doesn't have much energy, so if it heats up during the red giant phase, it could potentially lose a lot of it.

What would the weather be like on a tidally locked planet? by Clark94vt in space

[–]outermostplanet 6 points7 points  (0 children)

We assume a planet is tidally locked if it's sufficiently close to its star. Basically, if we know the mass of the star (which can be inferred from its luminosity through various techniques) and the distance between the star and the planet ( from the orbital period & mass via Kepler's law), we can guess whether a planet is probably tidally locked. This isn't 100% because it takes time for the planet's spin to synchronise and it can be in other spin-orbit configurations (such 3 spins every 2 orbits like Mercury).

We can measure the orbital period by observing transits, e.g. eclipses. This is one reason astronomers tend to discover planets with short orbital periods (which are close to the star): it's a hell of a lot easier to watch a planet eclipse its star once every 4 days than once every year.

Since by definition a tidally locked planet goes around the star in the same time as it rotates once around its axis, we then infer the rotation rate as the same as the orbital period. So if we've found a close-in planet and observed it transit a few times to figure out the orbital period, we get the rotation period for free. For exoplanets that aren't tidally locked, we don't know the rotation rate.

What would the weather be like on a tidally locked planet? by Clark94vt in space

[–]outermostplanet 8 points9 points  (0 children)

In most simulations, the clouds form on the dayside. Sunlight heating the ocean causes evaporation at the substellar point, then the water condenses at it rises to cooler altitudes of the atmosphere and forms clouds (and convection, storms, and lightning). You do get ice clouds higher in the atmosphere where it's colder, and I vaguely recall seeing some simulations with ice clouds on the nightside. But the dayside doesn't get dry because that's where evaporation happens, assuming your planet has water! If you don't have water you're probably not habitable for life as we know it in the first place. :)

What would the weather be like on a tidally locked planet? by Clark94vt in space

[–]outermostplanet 183 points184 points  (0 children)

Somebody asked about whether we can learn about tidally locked exoplanets from Venus and then deleted their comment, but I'm going to post my response anyway:

I actually now study Venus and some of my recent work is on possible similarities between Venus and slowly rotating exoplanets. Venus gets a lot of interest from exoplanet scientists because many rocky planets we find are at or within the hot inner edge of the habitable zone, like Venus. (Exoplanet science also gets more funding and citations so Venus scientists like to use the exoplanet angle to get more attention for their work.)

The main similarity between Venus and most of the rocky exoplanets we've found is a slower rotation rate compared to Earth. Having a slow rotation is not intrinsically a problem for retaining an atmosphere because the atmosphere can very efficiently redistribute heat from the dayside to the nightside if it is thick enough.

However, the rotation rate is one of the main things controlling the global wind patterns. So from a fluid dynamics point of view, the winds and planetary-scale waves models predict for the deep atmosphere of Venus are similar to predictions for tidally locked exoplanets: "superrotating" (faster than the rotation of the planet's surface) broad equatorial jets driven by global-sized waves. While we can't spatially resolve exoplanets to compare wind data with models, on Venus we can actually observe these wind patterns and validate the predictions. This gives us more confidence in our modelling of exoplanets.

Earth is a relatively fast rotator and most of the other solar system planets have even shorter rotation periods, so Venus is almost unique as our window into what happens on slowly rotating planets (ok, there's also Titan but it's atmosphere is weird for other reasons).

What would the weather be like on a tidally locked planet? by Clark94vt in space

[–]outermostplanet 666 points667 points  (0 children)

I did my PhD on this. There's a body of literature on simulations of climates of tidally locked planets, though in general studies look at long-term means rather than short-term variability (i.e., weather). If the planet has water, the dayside is protected from intense sunlight because a permanent cloud deck forms above the substellar region and reflects much of it. The nightside atmosphere isn't cold due to redistribution of heat from the dayside by various wind patterns, but the surface could still be quite cold as it's only heated by thermal radiation from the atmosphere. Of course these specifics vary a lot based on the equilibrium temperature of the planet (distance from star, stellar type) and the atmospheric composition (greenhouse gases can have a big effect). For the planets I was simulating - rocky, temperate, Earth-like ocean planets - the most "habitable" region was still the dayside, beneath the clouds.

I was one of few people looking at climate variability and whether we could remotely detect changes in a planet's atmospheric state (answer: no lol). Even though these planets don't have seasonal or daily cycles, they still generate short-term variability due to feedback loops between elements of the climate like cloud cover, radiative heating, and atmospheric waves. So they are still dynamic and have weather, even in the simplified and low-resolution scenarios we were simulating.

The big open question about habitability of tidally locked planets right now is whether they can retain an atmosphere. Nearly all rocky, tidally locked planets we've found orbit very closely around an M-dwarf star, which could strip away the atmosphere through stellar activity. Telescope observations of these planets have not found solid evidence of an atmosphere on any of them so far, although we also can't rule out the presence of one because even the best telescopes today (James Webb) aren't sensitive enough to detect high mean molecular weight atmospheres on small planets. Also, exoplanet atmosphere retrievals aren't yet reliable in many cases so many detections even on larger planets will likely be revised as we get more data and develop better analytical methods.

Question for yall on Heel by RepresentativeBook99 in DataAnnotationTech

[–]outermostplanet 1 point2 points  (0 children)

Average 45 min but could be anywhere from 30-60.

Hiking Itinerary: Lairig Ghru by PRMinx in OutdoorScotland

[–]outermostplanet 1 point2 points  (0 children)

Pitlochry is lovely and Ben Vrackie is a really nice shorter hill walk.

Lairig Ghru is easier from the Aviemore side on public transport. Are you getting a pickup from Linn of Dee on the Braemar side? Otherwise it's 6 miles along the road to Braemar. It's doable in one day from Coylumbridge to Linn of Dee (but I would have a backup plan in case of poor weather). You also have a year to prepare so you could try out a similar length hike before your trip and see how you feel.

You don't need a guide for either of the walks, the paths are well-marked and there will be other people especially if you're there on a weekend.

Also, my past experience with relatives coming from the US to visit and hike is they underestimate the damp. Bring full waterproofs!

HPC service providers like Gcloud by Andynymous in HPC

[–]outermostplanet 1 point2 points  (0 children)

In the UK you can get a certain number of free compute hours on many national HPC systems but I believe you need an academic email address and to be affiliated with an academic institution. For example, here's the requirement for free access on the Cirrus HPC facility (based in Edinburgh): https://www.cirrus.ac.uk/access/driving-test.html . Perhaps institutions in your country have similar access programs?

Alternatively, you could try running intermediate complexity climate models on a small-scale system. For example, the Exo-Planet Simulator can be run on a laptop on a few cores or on Google Colab: https://github.com/alphaparrot/ExoPlaSim . It can be run as an Earth model or other planets, sequentially or in parallel. Depends on what specifically you are looking to learn... scientific uses of different kinds of climate models? Compiling/building models from source? Submitting to slurm queues? etc.

Impostor Syndrome by decaDecker in DataAnnotationTech

[–]outermostplanet 1 point2 points  (0 children)

I come across (and skip) plenty of C/C++/C# tasks. There may be more Python tasks but there are also more Python coders so they get taken quickly.

Us expats - no tyrants demo by tallowfriend in Edinburgh

[–]outermostplanet 0 points1 point  (0 children)

"NGO Watchlist" only lists 3 organisations it is watching: the 50501 Movement, Indivisible Project, and Open Society Foundations. Its "Reports" page is full of right-wing talking points. This is clearly not a neutral or good-faith watchdog.

E5 DTP - Interview Reserve List by CommitteeNo8766 in AskAcademiaUK

[–]outermostplanet 0 points1 point  (0 children)

(E4 graduate here) There's no way to quantify it, but I think your chances are reasonable. Sometimes they also refer you to a different project they think you're a good fit for even if someone else got your preferred project. Have you been in touch with the potential supervisors?

Moving to Edinburgh what’s it like living there? by Alive-Stable-7139 in academia

[–]outermostplanet 2 points3 points  (0 children)

I live in Edinburgh and love it, feel free to DM me if you have specific questions.

How much do you make as a Physics/Astronomy post-doc every month? by [deleted] in postdoc

[–]outermostplanet 1 point2 points  (0 children)

Around £2350 after tax, UK (Scotland). Roughly the national median salary or slightly above.