While heading back up north, their flight path mimics an S-shape which they follow to save energy while navigating the wind systems in the different hemispheres.

在向北返回时，它们的飞行路线呈 S 型，在不同半球的风系统中导航时，为了节省体能，它们遵循 S 形飞行轨迹。

Also beset by heavy winds, the fires in Wisconsin flared, creating a firestorm: the heat from the fire was so powerful that it formed its own wind system.

同样受到大风的困扰，威斯康辛州的大火燃起，形成了一场火风暴：大火燃烧产生的热量太过强大，致使其形成了自己的风系。