If you compare the s orbital with the bottom lobe, these have a different sign so they're going to destructively interfere.

如果你们比较s轨道和下面这叶，它们正负号相反,所以它们相消干涉。

麻省理工公开课 - 化学原理课程节选

So I changed the colors here to show that these are 2 p orbitals with an opposite phase or an opposite sign.

我这里换了一种颜色,表示2p轨道,不同的相位或者是正负号。

麻省理工公开课 - 化学原理课程节选