In one study, biochemist William Frey, who has been researching tears for as long as he can remember, found that emotional tears caused by distress or grief contain more water than normal tears. He discovered that reflex tears are 98% water, while emotional tears also contain stress hormones that are excreted from the body when you cry!
All the different types of crying, whether from an onion or a melt down, are curated by your body give you exactly what you need. Stressed? It'll release your stress hormones. Is your eye stinging? Your tears will flush it out with good old h20.