Chapter 03 of 5
Life Under the Lid
The 4°C density maximum and the secret to winter survival.
- The Anomaly
A Density Peak
Most substances reach maximum density when solid. Water hits its peak density at 4°C (39.2°F), while still a liquid.
- Thermal Turn
The Turn of the Lake
As autumn air cools the surface, water becomes denser and sinks, pushing warmer water up in a cycle called overturn.
- Paradox
The Hitting Point
Once the entire water column reaches 4°C, the cooling process takes a strange, counterintuitive turn.
17 more cards in this chapter
Could you answer this?
At what temperature does liquid water reach its maximum density before it starts to expand again?
🧊 Why Ice Floats
- 01The Buoyancy ParadoxWhy does solid H2O defy the laws of physics and float?
- 02The Geometry of ColdDiscover the molecular architecture of the hexagonal lattice.
- 03Life Under the LidThe 4°C density maximum and the secret to winter survival.
- 04Exotic Ices & Deep PressureHot ice and extraterrestrial forms beyond the Earthly norm.
- 05The Molecular MastermindHow a 104.5-degree angle dictates the fate of the biosphere.