Fishing boats in Nice Harbour - their colours seem to rhyme with the beautiful Light
When writing the piece about the painters who settled on the French Riviera, I noticed how many people attributed their choice to the area’s fabulous light. Indeed, the Cote d’Azur (Blue Coast) did not get its name for nothing. The light is clear and bright and the colors strong. Feels a bit like New York on a clear September day with no mist and visibility for miles. Quite different to Tel Aviv's summer when days are misty and visibility low. Claude Monet described the light on the Cote d’Azur with these words: “It is so beautiful, so bright, so luminous. One swims in blue air, and it is frightening”.
The Rade de Villefranche-sur-Mer to the East of Nice - such visibility almost every Day
Bright light, clear air and far-distance visibility are a function of humidity. The less water in the air, the better the visibility. That’s why you can see so far from Swiss mountains or the towers in New York during fall and winter. The air is too cold to carry much water. The photons are not scattered by billions of water molecules and travel unimpeded.
The incredible luminosity of the French Riviera must be caused by this phenomenon: dry and cool air which allows light to proceed without being absorbed. But how is it possible that there is cool air in the Mediterranean? During summer it is covered by hot air layers from the Sahara. Every summer, the seasons (or the tilt of our earth axis) move the Mediterranean below Sahara’s water-starved air layers. Not surprisingly, the air absorbs all the water it can. The Mediterranean loses every year more water than it gets from its rivers.
Not only Saharan Air covers the Mediterranean but also Saharan Dust - NASA photo
How saturated the air is over the Mediterranean is visible on the Ligurian coast. When the humid air hits the Apennine behind Genoa, it rises and forms clouds immediately. The few degrees in temperature difference due to altitude reduces the air’s capacity to hold water. Vapour condensates. Cloud formation kicks in during morning hours. By early afternoon it often rains. It makes Genoa a rather muggy place during summer. Once the rain stops, cool and dry air flows down from the hills again. The fresh breeze allows the Genovese to open their windows to cool their homes.
Our Sail Boat - the Althea - in 2020 near Portofino (east of Genoa) with the typical Cloud Formation over the Apennine
The situation on the Côte d’Azur is similar. Hot, saturated air flows inland during the day. But there is one big difference. The mountains behind the French Riviera are a good 20 kilometres from the coast. Clouds do not form near the shore but further inland. The hills behind Nice and Cannes are famous for their violent thunderstorms. When saturated air rises quickly over the Alps, water droplets freeze. Ice rains from the sky. Since they usually melt on the way down, we experience mostly big water drops. Quite often though hail reaches the ground and pummels cars, roofs, fields and the wines.
The Thermal Cycle is driven by the Sun and reverses every Dayu
Once the hot air mass has cooled down and shed its water, it flows toward the sea again – a process that starts in the later afternoon. This breeze is called Montana – often confused with the Mistral. But the Mistral does not reach the Côte d’Azur. It peters out at Toulon. The dry and cold Mistral is the main reason why Marseille is considerably less muggy than Genoa or Savona. The Montana's cold and dry air covers the French Riviera from the evening to the next morning and produces the condition for the exceptionally bright light which we enjoy in as much as contemporary painters did.
The Humidity Level in Cannes is considerably lower than in Savona which is as wet and humid as its bigger neighbour Genoa
The cool and dry air also allows the last observatory in France to stay open. The night sky is so clear that stars can still be observed. Ever heard of the International Dark Sky Reserve? Learned about when researching for this blog. An area spanning 2’300 km2 with 75 towns and villages committed to reduce light pollution. The Calern Astronomical Observatory in the Alpine foothills north of Cannes is open all year and allows you to see more than 3’000 stars during a clear night.
The Calern Astronomical Observatory is about 50 km north of Cannes
Am not a meteorologist and had to find the cause for the French Riviera's exceptional light myself. Having done my pilot license two years ago helped. One of the subjects we were examined in was meteorology. It is fascinating to understand how weather develops. The interaction of sun, air, sea and land gives us our daily weather and the Côte d'Azur its exceptional light. It also makes the evenings cool after a hot day. So don’t forget to pack a light sweater for the evening. You will need it on the boat.
Light and Limestone Seafloor produce this turquoise Water Colour here in Nice
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