Venusian Snow. 

Venusian snow is an exciting thing in my opinion. It is metallic, and implies catalytic chemical reactions in the Venusian atmosphere. It's not an especially new thing, it's been observed long enough that various persons have conflicting opinions about it. This IMRAD is written to settle some debates.

In the introduction the paper explains how the snow is observed, by radar, and owing to the properties of radar and what it observes attempts to infer things are made. There's a huge range of possibilities, which are included. It ends with a brief note about the elevation of the snow. The elevation is synonymous with a given temperature and pressure. The snow may only be stable at a certain environment, but the implication is that it exists at at least two elevations.

In the methods section the data came from Magellan, but was fed through some neato-skeeto computer program someone made. 

In the results section the snow line is seen to vary in elevation by 3.5km. The mountain range in question, Maxwell Montes is 11 km tall, Mt Everest is 8.8km tall. So this is the peaks of a mountain range with a little less than a third from the top eligible to catch snow. There is much notation concerning potential flaws in the data which can undermine the conclusion. DAVINCI will be able to make a better observation than Magellan did.

The second section of results is arguing a case for 'snow-shadow'. Rain-shadow on Earth refers to the way mountains catch more rain than surrounding valleys by interfering with wind, compressing humidity, and forming a downwind low pressure pocket. None of those mechanisms are super safe to apply to Venus, but the team observes where they can see the metal-snow, and then what physics can bring it about are free-game to speculate on. They didn't do the speculating from what I see, they just fired the starting pistol.

In the third section of results the nit-picks of potential misinterpretations of the radar data are pre-addressed. Basically the thing that can blow up this whole paper is a radar reflectivity or emissivity misinterpretation, so they are making sure everyone knows they double checked.

In the first section of the discussion they lob off a few possibilities that they do not think is true. If the Magellan data is bad, then the snow-line might be flat at a narrow elevation. If the Snow-line turns out to be an isotherm, then a lot of probes have been misreading surface temps. If the snow prefers to stick to certain rocks than others, then it should look messier than it does. It is not ruled-out that the snow may have come from an ancient incident and is not part of an ongoing process.

In the second section of discussion, assuming that all the data is good, then it must be the atmosphere dictating where snow is and isn't. This is reinforced by recent papers that are noting that the atmosphere below the cloud-deck changes in composition both periodically, and with latitude. So Maxwell Montes might be at a good latitude to catch snow.

The conclusions are many, but kind of revolve around the theme that the atmosphere is making snow, not plating metal on a rock-type as a chemical reaction. And also that there is a snow-shadow reaction, which opens up a new trail-head to study. It is possible an ecology exists, where the snow catalyzes atmospheric reactions, and the atmosphere makes, among other things, snow, implying that other chemical abundances may be seasonal, or latitudinally related to the snow. Possible negative and positive feedbacks.