Instead of hopping over to a retail store and blowing $200+ on an umbrella with a stand, you could create your own shady canopy with four wooden poles and a sheet (this one here is cotton muslin). Simply tie the a length of the fabric to the top of each pole, and now you have an instant canopy to protect you from harmful rays while you relax outside. Don't have grass? Use a bucket or pot filled with soil or rocks to hold the poles up.
[ Photo from Living Etc. ]