From: pharvey@mipos3.intel.com (Paul Harvey)
Subject: Re: Mediterranean climate (was: zones)
Organization: we who chose to live in mediterranean climates
	<1992Sep8.124750.765@calmasd.prime.com>
Date: Tue, 8 Sep 1992 22:31:27 GMT

In article <1992Sep8.124750.765@calmasd.prime.com> 
jhb@calmasd.prime.com (Jim Bishop) writes:
>While we are discussing climate zones, just what is a Mediterranean
>climate?  Can anyone define it in terms of Sunset climate zones?

It is much more coarser than the Sunset zones. Let's see, climate zones:
Tropical, Sub-Tropical, Mediterranean, Temperate, Sub-Artic, Artic. The
Mediterranean is a zone where most if not all rain falls in winter, which
is opposite to most climates where the heat of summer produces rain. The
Med zone is found in the lattitudes of about 50 to 30 degrees and on the
western edge of continents, Western US, Western Chile, Med Sea area, S.
Africa, S.W. Australia. The two major zones are Europe and US. In Europe,
it goes west to east, because the mountain ranges are that dirrection. In
the US, it goes north-south, because the mountain ranges are that direction.
In terms of Sunset zones, the Sacramento Valley is true Med climate, coastal
climates are modified Med with some, like SF or San Diego being more
sub-Tropical with greater daily variation in temps than winter to summer.

>The reason I ask is that someone recently referred to Seattle as
>having a Mediterranean climate.

It does, caused more by the rain shadow effect of the Olympic Peninsula. The
western edge of the peninsula is temperate rain forest. The further north
you go along the Pacific coast, the more summer rain you get. 

>The same has also been said of San
>Francisco; and locally (San Diego) I often hear our climate described
>as Mediterranean. 

They are in terms of rainfall, but climate is more sub-Tropical, like say
at about 6,000 ft in the tropics. Daily temp range is often greater than
seasonal. The cold water upwelling in the Pacific moderates the climate.

>Now to me each of these places has a very different
>climate.  San Diego and Seattle do not have the same weather. 
>However, I would say they are closer in terms of weather than their
>east coast counterparts, say Bangor and Miami...at least as far as hot
>and cold extremes go, but I imagine they (east coast) are much closer
>in annual rainfall terms.

Yes, Bangor is quite different from Miami. Miami is near tropical and gets
most of its rain in summer, Bangor is Temperate and gets near even year
round precip. Occaisionally, the dog days of August visit Bangor and the
residents get to experience tropical or near tropical conditions and 
occaisionally the Canadian express visits Miami and they get sub-freezing
conditions. The climates on eastern sides of continents are more severe
because the air comes from over land, assuming no mountains to block it.

>Coastal San Diego gets around 10 inches of rain a year, the inland
>valleys slightly more.  Most, if not all, of the rain falls between 
>November and March (though for the past several years all of it has
>fallen between February and April).  The climate is heavily influenced
>by the ocean.  We are rarely above 85 or below 45.  (Summer 65 to 80,
>winter 55 to 75.)  While this may sound like an advertisement by the
>chamber of commerce, I'm curious how this fits into the general
>description of a Mediterranean climate. 

In terms of rain, perfect. In terms of temp, it's sub-Tropical. S. Cal
also gets rain from the remains of Mexican Hurricanes that come north in
summer, this is the source of summer rain in the American deserts.

>Perhaps the problem is that the climate of the Mediterranean is quite
>varied also?  When I think of the Mediterranean, I think of Spain,
>southern France, Greece or Italy.

Yes, but cold weather is less likely because the east-west mountains block
cold northern air. Hot desert air happens, like your Santa Ana's.

>But I guess this should also
>include Northern Africa (probably closer in latitude to San Diego) and
>the coastal sections of the middle east.  From pictures I've seen
>(I've never been to the real Mediterranean.) I would guess San Diego's
>climate is close to say Spain's or maybe coastal parts or Lebanon and
>Israel.  Do any parts of the Mediterranean have the night and morning
>summer coastal fogs that so typifies California weather?

Not the same, we have fog due to cold water upwelling in the Pacific, typ
summer surface ocean temps are 45 in Seattle, 55 in SF and 65 in San Diego.
El Nino changes this somewhat, as we should know. This is an El Nino year
and ocean temps are up 5 degrees or so. I don't think you can find San
Diego's climate in Europe, more like 6,000 ft on Haleakala on Maui, don't
you think?

>Well, since I've raised this discussion I better offer a description
>of what I think a Mediterranean climate is.  My understanding is that
>it is is characterized by cool damp winters, and dry mild summers 
>with most of the precipitation falling in the winter months.  Also the
>growing seasons are somewhat backwards from most places.  Typically,
>the late summer and fall are times when most native plants are dormant
>and the winter and spring, when water is more readily available, is
>the growing season.  Also, below freezing temperatures are very rare.
>This description would fit a large portion of coastal California, but
>I don't think it would work too well with the Pacific Northwest. 

Why not? I'm just saying it is a coarse definition. 

>My
>assumption is that even though August and September can be dry there,
>they are still very much part of the growing season.  Also their
>winter lows are much lower than a typical Mediterranean climate.

You find conifers dominating the Pacific Northwest instead of decidious as
on the East coast. Why? Cool and droughty, not tropical summers and cool and
wet winters. You are right about occaisional cold air, this is because the
north-south mountains are poor at blocking Alaskan air masses. Of the Med
climates, the US experiences the coldest winters because of this, but summers
are less hot because of some isolation from the inland deserts.

>So, are there any meteorologists out there that can give a more
>accurate definition?  Or any other opinions (like I have to ask)?

I'm not a meteorologist and I don't play one on TV, but you have my opinion,
for what its worth. Are you saying you want to talk about the great Calif.
High and the Alaskan Low next? It is these permanent ocean systems that cause 
the backwards rain pattern. And all of this appeared just 12,000 years ago
when the ice began to retreat. Before then it rained in summer in the West,
Calif. was dominated by Avocados as well as redwoods.