General Weather Station Questions

[ProfessorBug]

It's my 40th birthday (no, no cards please), and I splashed out and got an Elecsa AstroTouch 6975. If you're not familiar with this, do an e-bay search for just the number '6975'. And be aware that you can get them for a tenner less at Maplin! Anyway, the instructions have been translated from the original Swahili with a reasonable degree of fluency, and it's possible to work out how to use all the features. However, I'm struggling to work out WHY you'd be doing some of these things. I'm hoping that these features will be common to other weatherstations, so perhaps someone will be able to explain to an 'old fogey'...

1. In the weather forecast bit (with the pictures of clouds, rain etc), it is possible to tap the screen, then change the symbol which the unit is displaying. Eg if the unit is forecasting rain, I can change the image so the sun is showing. Why on earth would I want to do this? Pehaps to play a hilarious prank on the Beloved... set the forecast to sun, then wait for the fun to begin as rain pours down on the freshly hung up washing? Am I missing something here?

2. Also in the weather forecast section, you can 'set the pressure threshold from 2-4hPa (default is 2)'. I assume that the station works by looking for a pressure change, and when this pressure change happens, then it does something - eg change the displayed icon. Why would I want to change the threshhold? Will this make the forecast change only in response to extremes of weather, eg on 2hPa It'll forecast rain if drizzle is coming, but at 4hPa, it would require an impending biblical flood to get the rain symbol to show? Does anyone else have this ability? What threshold do you use?

3. Same questions for the storm warning. Default is 4hPa, but can be set from 3 to 9. Presumably if I set it to 9 it would only go off for incoming tornadoes?

4. To the left of the fluffy clouds is a section of screen labelled 'tendency' which displays either an up arrow, a down arrow, or nothing at all. I've read the manual cover to cover several times (sometimes I have difficulty getting to sleep at nights), and nowhere are these arrows explained. Tendency of what? Tendency of me to get hit because the Beloved's new hair-do has gone frizzy due to a mysteriously un-forecasted downpour? I feel in my water that it should be related to atmospheric pressure, but the unit has a lovely 12 or 24 hour histogram history of pressure which makes it plainly obvious whether the pressure is rising or falling.

Thanks in advance for any light you may be able to shed on these mysteries.

ProfessorBug