According to an aspect of the present invention disclosed herein, there is provided an umbrella, comprising: a shaft; a first canopy; and a second canopy, wherein: the first canopy has alternating solid material and open sections; the second canopy has alternating solid material and open sections; the first canopy is attached to the shaft above the second canopy; and the first canopy and the second canopy are configured to rotate relative to each other around the shaft. A second embodiment is an umbrella, comprising: a shaft; a first canopy; and a second canopy, wherein: the first canopy is made of a polarized translucent material; the second canopy is made of a polarized translucent material; the first canopy is attached to the shaft above the second canopy; and the first canopy and the second canopy are configured to rotate relative to each other around the shaft.

Techniques are disclosed for modular outdoor umbrella systems comprising an umbrella frame, a substantially transparent canopy and a substantially opaque canopy. Initially, the substantially transparent canopy is removably installed on the umbrella frame by a user. This first canopy provides warmth and visibility during the colder seasons while providing protection from the ultraviolet rays of the sun. During the warmer seasons, the user interchanges the canopy with a substantially opaque canopy. This second canopy provides shade and cooling effect. The decision to interchange is based on a number of factors. These include performance attributes of the canopies, the prevailing environmental conditions and personal preference(s) of the user. In embodiments, a multiplicity of canopies are provided that can be modularly and removably installed by the user as needed based on the above factors. In other variations, a heatshield cover is provided that can be removably deployed over an underlying transparent canopy based on the above factors.

An improved umbrella is provided including a collapsible support structure, a primary canopy disposed over the support structure and defining a number of holes and an upper opening therein, a secondary canopy operably secured to the primary canopy to overlap the number of holes and a tertiary canopy operably secured to the primary canopy to overlap the upper opening. The alignment of the secondary canopy and the tertiary canopy over the holes in the primary canopy enables the dissipation of high air pressure formed within the interior of the umbrella caused by winds contacting the umbrella while maximizing the structural integrity of the umbrella.