There are two snowflakes on that panel. The orangeish one means the temp. is between 40 F and 33F. The red one glows when the temp. is 32F or lower. Hope this helps.
Air Conditioning
yellow snowflake indicates 33 degrees to 40 degrees. the red snowflake indicates anything freezing or below.
its below freezing temperature
Orange Snowflake Beware of Frost on road Next one is a Red Snowflake Beware of Ice on the Road
mercury
The answer to your question is that the snowflake appears when thoutside temperature drops to 40 degrees or below, it then changes to red when it is 32 degrees and below, thus letting you know when it is freezing outside so you know how to hand le the roads.
Mercury is not a magnetic matertial. Notes indicate that it is weakly diamagnetic, i.e. it is repulsed by magnetic fields. So some mercury alloys would also be weakly diamagnetic. Notes indicate that at very low temperatures (4K), mercury becomes a superconductor and it becomes a much stronger diamagnet (repelled). Apparently this magnetizes the mercury at this low temperature. See links.
It indicates that the mercury expands much faster in reaction to change in temp. If the glass expanded at the same rate as the mercury does, the level of mercury would not change.
There are two of them. Yellow if the temp falls between 1-4 deg c, red if it is 0 and under. Sorry not sure of the f values.
I think there were 2 types of displays, so you could check in the Owners Manual for the specifics(See Related Questions)
The reverse of the Winged Liberty Head ("Mercury") dime displays an ancient fasces, the symbol of power and justice, set off by an olive branch of peace. Plus the words "UNITED STATES OF AMERICA"; "E PLURIBUS UNUM"; and "ONE DIME".
If your asking about the small picture of a wrench, it's a service interval reminder light. It automatically comes on every 4,800 miles or 358 days after you clear it. It indicates routine maintenance.