Climate and Biome Overview of /rose/, /yeah/, and /haha/
Preface
This climate and biome overview is done with the new expanded poles in mind - the bottom of the map is now at 75th parallel south instead of 90th, generally making the climate on the map warmer.
This overview is made with the assumption that the niji continent is a big enough landmass to generate sufficient monsoon. While milder than Asia or, to a lesser extent, the holo continent, I consider it still strong enough to have a major influence over the climate and seasons of its eastern coast, especially when taking into account the orographic lift from the ridge in /haha/ and lazulight. I consider this decision justifiable due to the presence of two major rivers on the map originating from the area, which suggests a decent amount of precipitation that could be interpreted as an indication of monsoon climates. However, this is not strictly necessary. If it is decided that the niji continent does not generate a significant monsoon, all the climate zones below will have lower, but more evenly distributed precipitation (changing w to f).
Some might notice that the portion for /rose/ is longer than /yeah/ and /haha/. This is primarily due to two factors. First, the more elongated shape of /rose/ and its spread further inland results in it having a more varied climate, necessitating more words to describe it fully. Secondly, as the cold current flowing through their coast originates in the polar sea, /rose/ is described first, and aspects that apply to multiple countries is often explained there to reduce duplications between the sessions.
It should be noted that the climate zones suggested are meant to be a generalised overview - local conditions such as terrain and human(oid) activities can create microclimates. In extreme cases, a city built on a steep slope in the right direction can result in part of it being put in a different climate.
It should also be noted that the climate zones do not perfectly correspond to the biome zones. This is partly because the simplicity of Koppen climate classification sometimes gross over details contributing to its natural environment, but it is also because a biome can, to a degree, create its biome. As such, forests tend to be spread further than the climate zone indicates, and in case of a catastrophe destroying a significant part of the forest, the regrown forest will likely be smaller before it gradually spread out once again.
/rose/ Climate
Cold, dry stream from the southern polar ocean renders its southern lowland to be a consistently cold place. Northern /rose/ is relatively far from the coast, which means it will likely have a significant difference in temperature between day and night. That said, the monsoon of the continent means (relatively) wet air from the ocean will reach the land during the summer season, giving the land a more distinct rainfall pattern.
As such, while most of the land can still be considered continental/microthermal (D), its winter will be significantly drier (w) - most rain and snow of the land will come during the summer season.
In conclusion, southern /rose/ will likely have a subarctic monsoon climate (Dwc/Dwd), with the more southern part being colder. That said, by definition most of its land will not be frozen all-year-round, with at least one month having an average temperature above 10 degrees Celsius. It is a relatively uncommon climate type, seen mostly in eastern Siberia and parts of southern Tibet.
Northern /rose/, on the other hand, will likely lean closer towards continental monsoon (Dwa/Dwb... mostly Dwb), its continentality partially offset by orographic lift. It is most commonly seen in outer Manchuria and eastern Mongolia.
The southern coast of /rose/, due to its high latitude, cold current and monsoonal south wind, might have a thin strip of tundra climate (ET), where the warmest month averages above freezing point, but below 10 degrees Celsius (usually).
/rose/ Biome
The natural environment of /rose/ will likely be defined by boreal forest, also known as taiga. The relatively high variation of precipitation between seasons means the forest will likely be seasonal, and dominated by coniferous trees like larch, spruce, fir, and pine.
In the inland region of northern /rose/ the boreal forest might begin to give way to grass and shrub, especially in drier areas. These areas will resemble the eastern Eurasian steppe. If there is a significant reduction in vegetation, such as wildfire or extensive logging, the grassland might spread further across northern /rose/.
Near the southern coast of /rose/, the cold weather means only the most cold-resistant trees (like larch) can grow, and even then they will be sparser, with space in between likely occupied by lichen and wetland. In particularly exposed locations, the strong, freezing wind might result in tree growth becoming stunted and twisted, known as krummholz formation or tuckamore. Extensive logging in the coast will likely make it a true tundra.
The cold weather in southern /rose/ means only the topsoil might thaw during its summer season, with the deeper ground being frozen all-year, otherwise known as permafrost. This results in poor drainage of water, meaning that the land will be very waterlogged during the summer season, to the point it might well be considered impassable terrain. As such, it will likely form extensive wetland beneath the forest with minimal decomposition, making it a peatland. Peat can be harvested from it and, if dried, can serve as an excellent source of fuel for heating.
/yeah/ Climate
Similar to /rose/, the climate of /yeah/ is dominated by cold ocean current and monsoon, although its lower latitude means the land is, in general, warmer than /rose/. While annual precipitation and pattern are likely similar to /rose/, rain will be more common than snow due to the warmer weather. As such, the climate of /yeah/ can be described as continental monsoon (Dwa/Dwb, with more Dwa than northern /rose/). Compared with northern /rose/, this slightly warmer weather can be observed across Korea and inner Manchuria.
/yeah/ Biome
Due to the similar climate condition, the natural environment of /yeah/ will also be similar to /rose/, with its southern part being dominated by boreal forest (taiga) of conifer trees like larch, spruce, fir, and pine. In lower latitude and inland without significant mountains, the forest will similarly give way to shrubs and grass, rendering it more similar to temperate grasslands like prairie and steppe. Extensive logging of taiga in a short time frame might spread the grassland further south.
/haha/ Climate
Geographically, /haha/ is defined by its highland, with most of its land located above 2,000 metres. The higher altitude itself results in it having a colder climate, and it also prevents the majority of moisture from the niji monsoon from reaching it, rendering its eastern neighbour wetter and itself drier. However, the inland sea to the west should keep most of /haha/ sufficiently wet to not be completely arid. As a result, its climate is not heavily influenced by the monsoon, with its precipitation being distributed more or less evenly across the months.
The majority of land in /haha/ will likely be considered subarctic (Dfc/Dfd), although the lower northern valley and western coast might have a humid continental climate (Dfb) that extends to the shores of the inland sea. This is a relatively common climate zone, commonly seen in the northern Great Lakes area and Eastern Europe.
The climate becomes steadily colder towards the south and towards higher mountains. The tip of the southern hills, especially the one with snow cap marked on the map, can be fully covered in ice year-long as icecap (EF), with tundra (ET) serving as a barren transition zone between the inhospitable icecap and the relatively habitable continental climate zones.
While likely not significant or consistent enough to cause a change in climate zone, the orographic lift generated by mountains means many places west of the ridge will likely experience foehn wind, sudden bursts of warm, dry air downhill.
/haha/ Biome
Similar to /rose/ and /yeah/, the natural environment of /haha/ will likely be dominated by boreal forest ("taiga"), with the possible exception of temperate grassland in the northern lowland and western coast, especially if there is extensive logging in those regions. Compared with the taiga in /rose/ and southern /yeah/, /haha/ forest will likely be predominantly evergreen due to lack of distinct wet/dry season.
Climate Zones Reference from Geodiode
Geodiode is a site that I recommend if you want more details on the environment a given climate has.
Biome
Taiga: https://geodiode.com/biomes/taiga
Grassland: https://geodiode.com/biomes/grasslands
Climate
https://geodiode.com/climate/continental
https://geodiode.com/climate/subarctic
https://geodiode.com/climate/tundra
https://geodiode.com/climate/icecap