Re: Mesozoic snow - refined

[MariusRomanus@aol.com]

Phil Bigelow wrote:

>> The currents and the temperature flux of the Interior Seaway can only be 
>> hypothesized.  There was a paper published a few years ago on this very 
>> subject (using computer modeling, as I recall).  Various scenarios were 
>> discussed.  Once scenario involved a current pattern and temperature similar 
>> to that of today's Gulf Stream. <<

Yes... The trouble with SST fields... just like I explained in my first post.

>> Did a north polar ice cap exist during the Maastrictian?  Possibly.  The 
>> north end of the Interior Seaway had finally closed off, and warm Tethyan 
>> water could no longer flow northward to moderate the Arctic Ocean 
>> temperatures (and cold Arctic Ocean water couldn't flow southward). <<

Yes... as in dry land allowing continental polar air masses to form... Just 
like I said in my second post. Continental polar air for the winter months was 
still colder than that produced during present day summer months. And of 
course, I didn't say arctic air masses, since no large permanent ice cap 
apparently existed.

>> If the Hell Creek area had a climate similar to today's coastal Florida (and 
>> most people think it was similar), then depicting the Hell Creek landscape 
>> as snowy during the winter would be an exaggeration of the available 
>> evidence.  That is not to say that it didn't *occasionally* snow in that 
>> area, but to portray the Hell Creek region that way is stepping over the 
>> line a bit. <<

Of course, I never did say a snowy winter was the norm. And when it did snow, 
it wouldn't have lasted or really even accumulated to begin with, like I 
already said.

>> Most paleobotanical evidence points to a WORST-CASE winter temperature 
>> regime for the Hell Creek region similar to today's coastal Olympic 
>> Peninsula during the winter.  In other words, minimum temps. of 35-40s F., 
>> with occasional dips below 32 degrees F. caused by high pressure fronts 
>> coming from the continental interior.   "January" mean temps of
55-60 degrees F. would be more typical for the Hell Creek region. <<

Yes... Basically what I already said in both of my posts. Low 30s will give you 
the mixed precip, depending on the source region and temperature structure of 
the air column anyway, and below freezing would give you snow... as I already 
mentioned. Oh, and as I stated in my first post, the flora sample we have is 
mostly coastal after all. Palm trees along the coast of western Ireland doesn't 
mean the rest of Ireland has them. And really, the presense of palm trees 
doesn't mean that part of Ireland is like Florida to even start with, just as 
James Cunningham pointed out. (Take a gander at my "A bolide did it!... No, not 
really" posts from Feb. I went over the effects of the Gulf Stream of Europe 
when discussing the thermohaline circulation and ice ages.) It's obvious that 
you wouldn't see a white christmas along the margins of a warm seaway... but 
the further away you get from it, especially to the north and toward the 
interior, the better the chance that dinosaurs were playing!
  i!
n a light snowfall from time to time. Hell Creek, after all, is a sample of 
only one particular region. (Funny part is that we are severely generalizing 
when it comes to the climate here, and not even taking into account 
topographical influences, as in my remarks made in the March thread "Ice Sheets 
Caused Massive Sea Level Change During Late Cretaceous".)

Kris
http://hometown.aol.com/saurierlagen/Paleo-Photography.html