Geography and Appearance of an nitrogen/ammonia planet

The planet in question is this one. Approximately three quarters the size and half the gravity of Earth, an atmosphere 25% as dense as the Terran one which mainly consists of Nitrogen with small percentages of Oxygen and Carbon Dioxide. Orbiting a Proxima Centauri, a red dwarf, at the outer rim of the habitable zone, the planet is relatively cold, with average surface temperatures ranging from -80 to -30°C. Volcanic activity is non-existent or minimal at most. The sky takes on a dark greyish-brown color, becoming reddish at sunrise and -set and during dusk as well as around the star.

The planet rotates within 27 hour; its orbital period is approximately 20 days. The orbit is rougly circular; the axial tilt of the planet is relatively high (34°).

Seas of liquid ammonia cover approximately half of the planet where it is not frozen. Color of the sea varies from deep blue to golden bronze, varying by the amount of metals dissolved in the ammonia. The colors render the structure of oceanic currents.

I have heard that ammonia quickly and easily dissolves soil, so I imagine that the terrain, especially the coastlines, would be very ragged. I imagine that ammonia would only boil or evaporate in few places and quickly rain down, which means that most rivers would be periodic and located close to coasts, albeit leaving distinct marks on the terrain.

The topmost layers of the rock or soil will probably contain nitrogen compounds, their concentration rising as you get closer to the nearest coast. This will be interesting especially if those compounds have distinct colors.

Terrain close to the coasts will be very ragged, full of small ammonia lakes or ammonia ice patches, canyons and valleys made by rivers while further away from the sea, it will mainly consist of plains and rolling hills with occasional meteorite craters.

Because ammonia does not have a density anomaly like water, I imagine that the further north or south you travel, the higher up the sea will be frozen. While only the deepest areas of the equatorial lakes and oceans will be frozen, the poles will be covered in vast and very flat ammonia sea plains and glaciers.

My questions are:

• Is my description plausible?
• If not, why? What must be changed?
• Can you add anything? Weather system? Climate? How would ammonia clouds look?

posted almost 8 years ago

MedwedianPresident‭

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