Library · Light & photoperiod
Latitude Comparison.
Latitude Comparison Tool
Compare daylight and natural DLI between two locations across the year. Useful for greenhouse planning, outdoor crop selection, and indoor solar replication.
Why compare latitudes
- Outdoor crop selection — your latitude determines which crops can complete a full season. A short-day flower triggered too early can mean an unfinished crop at frost.
- Greenhouse supplemental lighting — at 60°N in winter, you supplement 8+ hours per day to extend photoperiod. At 30°N you might supplement 2-3 hours.
- Indoor solar replication — replicating Costa Rica's light pattern indoors anywhere requires knowing what that latitude actually does seasonally.
- Migrating cultivars — bringing heritage varieties from one climate zone to another requires understanding the photoperiod transition.
- Harvest planning — DLI accumulation through the year drives biomass; comparing locations helps predict yields.
Latitude reference points
| Latitude | Cities | Day length range | Notes |
|---|---|---|---|
| 0° (equator) | Quito, Singapore, Nairobi | ~12 h year-round | Stable photoperiod; tropical agriculture |
| 15-25° | Mexico City, Mumbai, Hanoi | ~10.5-13.5 h | Mild seasonal variation; tropical/subtropical |
| 25-35° | Phoenix, Casablanca, Sydney | ~10-14 h | Subtropical; year-round outdoor production possible |
| 35-45° | San Francisco, Tokyo, Athens, Buenos Aires | ~9.5-14.5 h | Mediterranean / temperate; productive but seasonal |
| 45-55° | Seattle, Paris, Vienna, Vancouver | ~8-16.5 h | Cool temperate; greenhouse-supplemented |
| 55-65° | Stockholm, Helsinki, Anchorage | ~5-19 h | Boreal; heavy supplemental lighting in winter |
| 65°+ | Reykjavik, Murmansk | 0-24 h (polar) | Extreme seasonality; near-impossible without artificial light winter |
Solar Replication mode tie-in
OAT's full Light Engine includes Solar Replication — driving fixtures to mimic any latitude's natural light pattern at any date. This is the tool to use to pick which latitude to replicate. Want strawberries to think they're at 45°N for short-day flowering? Or tomatoes at 20°N for stable photoperiod? See what those latitudes actually do, then have the platform replicate them.
Free under CC BY 4.0. Cite as "OAT Latitude Comparison Tool (openagriculturetechnology.com)".