The amazing cloud-repelling islands off Baja California (IMAGERY)


Satellite view Sunday (NASA)

While the eastern Pacific ocean off the west  coast of Baja Peninsula in Mexico  was absolutely draped in cloud cover Sunday and Monday, islands in the midst of these sheets of gray were clear skies oases.  How can this be?

The clouds form over the ocean because the chilly Pacific water creates a layer of cool air at low altitudes. When the air is heated just above the ocean surface, it cools and condenses into clouds and fog forming the so-called marine layer (which is held in place by a temperature inversion, in which the air – divorced from the cool sea surface – warms with altitude).


Satellite view Monday (NASA)

But over the islands, the layer of cool air required for these clouds to form is often absent since land masses and the air above them heat up quickly (thanks to the low heat capacity of land versus water).  And so, unless there is wind  to push the marine layer over the islands, they’re bastions of sunshine.


Wide satellite view Sunday (NASA)

At times, however, westerly flow and/or a sea breeze circulation set up so that the marine layer is pushed into the islands (see case below from Saturday).  This same phenomenon occurs in coastal California – especially in late spring and early summer leading to spells of dreary fog and gray skies, often referred to as “June gloom” .


Satellite view Saturday (NASA)

Further reading: What are Marine Layer Clouds and How Do they Form? | The Marine Layer

Jason is currently the Washington Post’s weather editor. A native Washingtonian, Jason has been a weather enthusiast since age 10.
Comments
Show Comments
Most Read Local

Heat Tracker

48
90-degree days year-to-date
Yearly Average
36
Record Most
67 (1980,2010)
Record Fewest
7 (1886,1905)
Last Year
24

At a Glance

Fri.

thunderstorms
76° /90°
Drop 20%

Sat.

partlycloudyday
71° /82°

Sun.

partlycloudyday
69° /83°

Mon.

partlycloudyday
71° /89°

Tue.

thunderstorms
72° /90°
Drop 20%

Wed.

thunderstorms
73° /91°
National Airport
Dulles
BWI

Right Now

D.C. Area Almanac

 
National
Dulles
BWI
Avg. High
 
Avg. Low
 
Rec. High
 
Rec. Low
 
Sunrise
 
Sunset
°F
 
 
°C
Next Story
Matt Rogers · June 24, 2014

To keep reading, please enter your email address.

You’ll also receive from The Washington Post:
  • A free 6-week digital subscription
  • Our daily newsletter in your inbox

Please enter a valid email address

I have read and agree to the Terms of Service and Privacy Policy.

Please indicate agreement.

Thank you.

Check your inbox. We’ve sent an email explaining how to set up an account and activate your free digital subscription.