Hi Brandon,

The two conjunctions are similar but used in different situations.

Quand conveys the sense of - "à quel moment"

Lorsque the sense of - "au moment où"

For example "You are washing up while (au moment où) your friend walks the dog.

So we have two continuous actions happening simultaneously.

It would sound odd to use "when" - "quand" in this situation.

Another scenario. Again you are involved in some activity when (à quel moment) the doorbell rings. 

Here we have another sudden action interrupting what you were involved in doing. 

Hope this helps.

Jim

Quand and lorsque are mostly synonyms when used in the sense of "at the time of". Lorsque is a bit more formal and quand is used more frequently. One difference is that lorsque cannot be used in questions asking "when". There are some slight differences (some say that lorsque pinpoints the time more closely than quand), but I leave that to the native speakers for comment.

Ethymologically, lorsque derives from "lors que", which means "at the time when". Maybe it is itself a contraction of "l'heur que"?