Additional Sites: Tumblr | Flickr | Vine | Weather Research | SF Giants Blog

 

Christina Loren is a Certified Meteorologist with an enthusiastic passion for atmospheric science.



The Beauty of Science: Why Autumn Leaves Burst With Color

By: Christina Loren

Fall color is gradually becoming more conspicuous in California as summer swiftly comes to a close. Vivid reds, oranges, yellows, and purple hues of changing leaves will paint beautiful natural scenery from September through November, although peak color only lasts for around one to three brisk weeks.

Hours of Daylight Over Cooler Weather 

Contrary to what some may think, the reason why leaves change color in autumn is predominantly the product of available daylight hours as opposed to changing weather patterns. Picture worthy foliage is caused by changes in the process of photosynthesis which means, “putting together with light.” Chlorophyll is a chemical that makes photosynthesis happen and responsible for the green color of leaves. As days get shorter in the fall there is less available sunlight for the production of chlorophyll, which slows and eventually stops. Resultantly stunning fall colors are gradually uncovered before leaves wither and fall off of trees. Variables like temperature, wind, cloud cover, and soil conditions widely influence color intensity and duration of the foliage exhibit although they are not the main cause for the metamorphosis. 

Not All Trees Have Changing Leaves 

There are two primary types of trees: evergreens and deciduous trees. Evergreens stay true to their designation and hold on to their green color all year long. Meanwhile deciduous trees shed their leaves annually in the fall and then in the spring they grow back as days get longer. Deciduous trees are often called ‘broadleaf’ trees because instead of thin needles, they have larger and wider leaves making for a substantial surface for the photosynthesis process. 


Peak Fall Color 

Lake Tahoe: Late September through October 
Napa Valley: Mid-October through early November 
Big Sur: Late October 
Yosemite: Mid-Late October 
Big Bear Lake: Mid-October through early November

Labels: , , , , ,

posted by Christina Loren @ 1:14 PM, ,




Promise Falls As We Usher In The New Season

By: Christina Loren

     The Fall equinox will take place on September 23, at 1:21 a.m. PDT when the sun crosses the celestial equator from north to south. The Equinox signals that the length of day and night on September 23 will be nearly equal, about 12 hours long. Soon after the Autumnal Equinox nights will get longer than days and temperatures will dive down considerably in the Northern Hemisphere. Those who are fed up with the oppressive summer heat will be happy to hear that days will continue to get shorter, hence cooler, as we transition into Winter. There is typically increased moisture in the air in Autumn as storms begin to line up in the Pacific Ocean. California's rainy season begins in October and with a developing El Niño in the Pacific Ocean, higher than average rainfall this year looks quite promising. 
      Often referred to as 'harvest season' Fall is the time of year when many delicious fruits and vegetables have reached full maturation. These delectable items are ready to be gathered, sold, and stored before damaging frost develops in the cold winter months. Animals also take advantage of the Fall season by building up fat reserves for migration or hibernation. Overall the Fall of 2015 offers hope for ample rain, delightful produce, and cooler weather that we can all look forward to. 




Labels: , , , , , , ,

posted by Christina Loren @ 12:48 PM, ,




What is the 'Blob' in the Pacific Ocean?

By: Christina Loren

     You may have recently read snippets online or heard brief mentions on television of the warm 'blob' in the Pacific Ocean. The 'blob' refers to an unusually warm area of water in the Pacific that spans from Baja Mexico all the way up the west coast of North America, extending into the Gulf of Alaska. Ocean temperatures are running around 3- 4.5º F warmer than average in this sprawling area and the abnormality is linked to unusual weather conditions occurring on the west coast. You may recall that last winter we received a fair amount of rainfall in the Bay Area, but Tahoe saw very little snow. This occurred because most of the weather systems that moved over Northern California had ample moisture, but were too warm to produce heavy snowfall. This phenomenon can likely be attributed, at least in part, to the 'blob' in the Pacific Ocean.

      In addition to atypical weather patterns, the 'blob' is also producing difficulties for marine life since this area of warmer than average water is lacking critical nutrients. Typically this area is known for "coastal upwelling" which helps to churn up phytoplankton necessary for the food chain of marine mammals from the depths of the ocean. Normal upwelling is not taking place in this area of warmer, stagnant water and it is in turn nutrient poor. With the combination of a developing El Niño and the 'blob' it looks like the 2015-2016 rainy season could be one for the record books, particularly in Southern California.


Areas of red indicate the 'blob' of warmer than average water in the Pacific Ocean
that was identified in 2013. It extends from Alaska to Mexico and will likely persist
through 2015.

Labels: , , , , , , , , , ,

posted by Christina Loren @ 2:05 PM, ,