With respect to clothing, both meanings of the word "light" apply when it comes to dressing for the heat.

While "light" as in "lightweight" should be straightforward, what is it about light shades, especially white, that make them the ones to choose when facing a heat wave? It needs to be understood that light is energy, and the sun sends the bulk of its energy our way via its powerful stream of visible light.

Depending on a range of physical and chemical properties, some things reflect much more light than do others. This is the key, reflected light means reflected energy, and absorbed light means absorbed energy, energy that is converted from that of electromagnetic waves to heat.

White things are white because we see light reflected from them. Objects that are dark, even in bright light, are efficiently absorbing light, and thus being warmed by it.

So, those who need, or want, to face the heat of a bright 90-degree or 100-degree day with a minimum of discomfort should consider "lightening up." By AccuWeather.com Senior Forecaster Jim Andrews