Charles Powell

Front cover: A view of smoking volcanoes in East Java (Indonesia). In the valleys is a layer of Stratus, while on the top of Mount Semeru a small pyrocumulus (also known as flammagenitus) cloud can be seen. Volcanoes emit small particles into the air which provide additional surfaces onto which the water vapour can condense. Therefore, pyrocumulus clouds can appear more dense than other clouds. If the heat source is large enough, the pyrocumulus may evolve into a pyrocumulonimbus. (© Nur Syaireen Natasya Binti Azaharin: Smartphone Category Winner, Standard Chartered Weather Photographer of the Year 2024)

The June issue of @rmets.org Weather is online now! This is a Special Issue, with contributions from prize winners at last year’s Early Career and Student Conference.

Plus, all the main articles in this issue are fully Open Access ✅

Check it out now: rmets.onlinelibrary.wiley.com/toc/14778696...

Spot the sea breeze!

Pic from www.netweather.tv

GitHub - rmkenv/disaster-data-replicator: Data pipeline for replicating NOAA's Billion-Dollar Disasters Database using NWS and FEMA APIs Data pipeline for replicating NOAA's Billion-Dollar Disasters Database using NWS and FEMA APIs - rmkenv/disaster-data-replicator

Not the answer but it’s a start github.com/rmkenv/disas...

The cloud has got its hat on today

Neat clouds from Bern, Switzerland. Lenticular (ish) and KH (ish).

Successful eclipse viewing with the Mark I Colander

Science in action

Undular bore clouds move over the Gulf south of Texas.

Can climate models reproduce observed trends?

The answer can be challenging. Our new review paper in Science Advances led by Isla Simpson and Tiffany Shaw @drshaw.bsky.social discusses challenges and ways forward in confronting climate models and observations.

www.science.org/doi/10.1126/...

Happy that our (@iccscambridge.bsky.social) JOSS paper on FTorch has been accepted and is now out. This is a really neat library, smoothly enabling coupling of ML models developed in PyTorch into Fortran code, now being used in various climate models (+ other scientific domains too). Well done team!

Moisture transport by convective overshoots in the tropical tropopause layer Deep convection overshooting the tropical tropopause offers the potential for significant transport of moisture into the tropical tropopause layer (TTL) by avoiding the cold-point temperature constra....

The cold tropical tropopause limits water vapour concentrations in air that rises into the lower stratosphere. Strong, deep convection can avoid this constraint, injecting moisture that influences chemistry and radiative balance.

Read our review article in Weather here!

doi.org/10.1002/wea....

Great, thanks for the info! I'll keep my eyes peeled.

Has this subsumed the annual climate dynamics workshop? Haven't seen any info advertised for it yet.

Perfect day for some coaching

The extreme cyclone headed towards Ireland & the UK is a direct result of the upcoming southern US snowstorm - strong cold air advection into the Gulf of Mexico leads to an intense baroclinic wave developing and rapidly deepening as it traverses the North Atlantic:

A map from the GFS weather model showing MSLP and jet stream strength at 00:00 UTC on Sunday 26 January 2025 across the North Atlantic. Three areas of low pressure (a cyclone family) can be seen simultaneously at various phases of their development.

A jet-stream fired up by the current North American coldwave will lead to a phenomenon known as a "Cyclone Family" in the North Atlantic.

Multiple deep low pressure areas develop and take a similar track late January (close to the British Isles)

More info: www.nature.com/articles/s41...

The potential is there for a very nasty storm for NW Ireland on Friday morning depending on the placement of the depression. UKV is particularly concerning showing gusts in excess of 100 mph (160 km/h) for exposed NW coasts.

Bar graph showing global ocean heat content change in the upper 2000 m from the late 1950s through 2024. There is a long-term warming in the time series.

ICYMI - 2024 was also the hottest year on record for our oceans. Unfortunately, we now say this every year. 🥹🌊

+ Data: www.ocean.iap.ac.cn
+ Study: doi.org/10.1007/s003...
+ Summary: www.carbonbrief.org/state-of-the...

Finalising some figures of an idealised deep convective cloud top. Reassuring when simulations resemble observations!

Ice crystals are beautiful!

Hurricane Season 2024 retrospective | Inigo by Charles Powell (University of Cambridge) and Ruth Petrie (Inigo) Key points Forecasts for the season Coming into the 2024 hurricane season, almost all forecasts pointed towards an above average sea...

Working with the climate science team at Inigo insurance, I've written a retrospective on the 2024 hurricane season. We look at why forecasts predicted such an active season, why activity died down during the climatological peak, and what we might expect in the future.

Check it out here!

Award details | Funding and scholarships for students | University of Exeter

Having had the pleasure to work on this fascinating project with the potential for big impacts across the globe, please do share far and wide with anyone interested in a cutting-edge PhD opportunity in lovely to develop a brand new source of atmospheric observations!
www.exeter.ac.uk/study/fundin...

At this time of year, it’s hard not to go slightly blind when taking cool cloud photos…

Our results highlight the difficulty in resolving and parameterising convection in climate models. The mixing statistics are time sensitive and localised, so high temporal and spatial resolution is needed to capture the mixing.

We also looked at metrics that quantify mixing. We identified a three-stage mixing process, each with distinct characteristics. It turns out the most efficient mixing occurs in a thin layer at the top of the plume.

To understand turbulent transport and mixing, we use a phase space where the fluid buoyancy and tracer concentration are the coordinates.

It turns out the mixing is much clearer in this space and clarifies the mixing process between plume and environmental fluid.

Diagnosing tracer transport in convective penetration of a stably stratified layer | Journal of Fluid Mechanics | Cambridge Core Diagnosing tracer transport in convective penetration of a stably stratified layer - Volume 997

My first PhD publication has just been released!

doi.org/10.1017/jfm....

We consider a buoyant plume with a passive tracer penetrating into a stably stratified layer. This idealised flow is representative of many geophysical flows, for example tropical deep convection.
🧵⬇️

Shelf cloud over the Centre for Mathematical Sciences in Cambridge earlier today

Hints of mammatus?