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FAQ: Difference between revisions
→What formula does Cumulus use for Dew Point?
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For Fine Offset stations if you don't have Cumulus running when DST ends, then when you start Cumulus up again, the catch up misses off the first hour after the time Cumulus was stopped. This is because the console memory does not time-stamp the data blocks and Cumulus does not remember the console data block used just before shutdown, after all depending on how long Cumulus has been stopped and the station logging interval, the old memory location could be overwritten by now. On restart it just tries to read the appropriate number of hours worth of observations back from the block now marked as latest. If it was stopped at 2200 DST and restarted at 0600 standard time, Cumulus catches up with the last 8 hours worth of stored measurements as if going back to 2200 standard time, that means it stops at 2300 DST. At the start of DST, the catch up will duplicate the last hour that Cumulus was previously operating. (Stopping from 2200 standard time to 0600 DST the catch up goes back to 2200 DST or 2100 standard time). | For Fine Offset stations if you don't have Cumulus running when DST ends, then when you start Cumulus up again, the catch up misses off the first hour after the time Cumulus was stopped. This is because the console memory does not time-stamp the data blocks and Cumulus does not remember the console data block used just before shutdown, after all depending on how long Cumulus has been stopped and the station logging interval, the old memory location could be overwritten by now. On restart it just tries to read the appropriate number of hours worth of observations back from the block now marked as latest. If it was stopped at 2200 DST and restarted at 0600 standard time, Cumulus catches up with the last 8 hours worth of stored measurements as if going back to 2200 standard time, that means it stops at 2300 DST. At the start of DST, the catch up will duplicate the last hour that Cumulus was previously operating. (Stopping from 2200 standard time to 0600 DST the catch up goes back to 2200 DST or 2100 standard time). | ||
== What formula does Cumulus use for Dew Point? == | |||
dewpoint := tempinC + ((0.13 * tempinC) + 13.6) * Ln(humidity / 100) | |||
== What formula does Cumulus use for Apparent Temperature? == | == What formula does Cumulus use for Apparent Temperature? == | ||
It uses a formula from the Australian BOM - http://www.bom.gov.au/info/thermal_stress/#atapproximation | It uses a formula from the Australian BOM - http://www.bom.gov.au/info/thermal_stress/#atapproximation | ||