blue is a kind of color & dark means dark in color ->  dark blue is dark in color  dark blue is dark in color & as lightness in color of an object increases , the ability of that object to reflect light will increase & white is light in color ->  white colored object will reflect more light than the dark blue object  white colored object will reflect more light than the dark blue object & there is a white t-shirt & there is a dark blue t-shirt & t-shirt is a kind of object ->  the white t-shirt will reflect more light than the dark blue t-shirt  the white t-shirt will reflect more light than the dark blue t-shirt & if an object reflects more sunlight, than the object is more likely to stay cool -> the white t-shirt is likely to be cooler than dark blue t-shirt