Mishnah Berurah, siman Raish -cuf - tet,  2 halachas, both very interesting.  The first sif is about the rainbow. And I quote, the Mechaber : " When one sees a rainbow, he should say. Baruch  ata ... ha-olam   who remembers the covenant,is believed in his covenant, and establishes his word."  the Mishnah Berurah will explain, you can look inside for yourself for the intention one is meant to have when they say these words.

Alef in the Mishnah Berurah ;" Its not worthwhile  to tell your friend that there is a rainbow, because of  "moitzy dibah"  Now moitzy dibah is a kind of lashon Hora, slander,   But when you tell your friend that there is a rainbow, what is the lashon  hora that you are saying.  I think the answer is in sif katan dalet. And I quote the Chofetz Chaim " that is to say, that I will not Yavirenu, even though there are many reshayim (evil people) Yavirenu  - I will not go over my word , (and even though there are wicked people in the world now,  and the world might deserve to be destroyed) I will not destroy the world.

So that I think is the answer to what the moitzy dibah is.  If you tell your friend that there is a rainbow in the sky.  You are telling him that Hashem would destroy the world now today because of the bad people that there are in the world,and only because of the oath that he made he is not doing it.

And if you look in the Biyur Halacha, - Ha Ro-eh Ha keshet, it says an interesting thing.  It is not written anywhere what the measurement of the rainbow  needed to be seen in order to say the blessing.  In other words, perhaps you would think that one needs to see the entire 1/2 circle. Or at least a1/4 circle.  the Chofetz Chaim comes to tell us, I think, that even a small amount of the rainbow, as seen in the picture I am sending with this letter, is enough. I looked in the Piske Tshuva, and it says, safec Brucha le Hakale, - In other words, and I spoke to a few people about this and it seems pretty strait forward.  When you see a rainbow. You should not say the Brucha unless you see the the full half circle. Consult your Rav on  how to be nohag today. By the way the next day, we saw a full total rainbow - stretching from Jerusalem to beyond the mountains of Jordan.  I live in Rainbow country , and when it rains, its rainbow time.  However, you have to very very careful because the Mishnah Berurah also tells us not to stare at the rainbow, but to look at it and say the blessing.  And if you do stare at it , G-d forbid, it could weaken ones’ eyesight.

So there you have, - Have the greatest Shabbas

Yours
Rb Yossi