Thunder is good, thunder is impressive; but it is lightning that does the work.Mark Twain
This calculator works on the assumption that between each growth stage of a tree's growth cycle, there is a chance for it to become 'Thunderstruck'.
These growth stages occur between 'Small Sapling', 'Sapling', 'Young' and the mature tree. Sapling occurs at 10% of total growth time and young at 50% growth time. Trees that are grown in the correct climate are subject to a 30% reduction in growth time.
*Cherry trees don't seem to follow the usual 10/50/100% stages. Multiple observations have come in that they follow a 1h/5h/10h pattern and this is what the calculator reflects (Note this is not 10/50/100% of time to maturity which is 1d+).
v1.5.1 ThunderCheck - A Thunderstruck Tree calculator for ArcheAge. James, Kyprosa