[woolcap]

"I ignored..." = I was aware, but consciously chose not to address it, but perhaps softer than, "I consciously chose not to address it. "I ignored the fact that the sun was out, and returned from the beach sunburned." (I knew the sun would burn me, but went out anyways, with perhaps a shade of not realizing how much I would get burned.)

"I was ignorant of..." = I was unaware. "I was ignorant of the fact that the sun causes sunburn, and returned from the beach sunburned." (I didn't realize the sun would burn me.