What is the definition of situational irony

Situational irony occurs when the expected outcome does not happen.  The outcome can be serious or humorous.

as much wood as a woodchuck could chuck if a woodchuck could chuck wood.

sadly it cannot chuck wood

recent news about two years ago indicates that a polish forestry student by chance unearthed at a depth of about 40cm (16 inches), during digging in a damp polish forest he found a 13-page manuscript into a thermos flask.

greek jew marcel nadjari was a aischwitz slave who witnessed how the nazi's built big death chambers and crematoriums and told how he was forced to escort fellow jews to the gas chambers. he accounts on this manuscript how the nazi's disguised this chambers to look like showers. also, he describes this place as a process of extermination from the chambers to the trains arriving to take the bodies.