What is that colour-changing tubular thing on top of the condos at Yonge and Carlton?

What is that colour-changing tubular thing on top of the condos at Yonge and Carlton?—Ian Topp, Cabbagetown

You may not want to hang it on your wall, but the fixture atop the Met tower is the result of a city policy encouraging new development projects to devote a portion of their budget to public art. Of course no one said such artistic endeavours couldn’t have a practical purpose. This particular piece, designed by Ottawa-based artist Adrian Göllner, pulls double duty as a multicoloured meteorologist. Ominously titled Harbinger, the device reads wind speeds using an anemometer and changes colour (via LED lighting) depending on how hard the wind is whipping: blue is for barely a gust, green signals calm winds, red means blustery conditions and magenta (marking wind speeds of 60 kilometres per hour and over) means it’s time to drag the family down to the storm cellar. Or at least time to haul in the patio furniture.