METEOROLOGY 302.1, SPRING 2004
CLASS NOTES FOR MARCH 12, 2004

By Alex Tungadi & April Coffey

 

 

Explained:

 

Today’s Weather Map

-       Snow can be seen over at Sierra Nevada

-       Outlining the coastline is a layer of Fog 8000ft thick.

 

 

The definition of two methods of cooling

-       Conductional Cooling- occurs by the feeling of temperature adapted to the surface.

Picture putting your hand on top of a hot hood of a car. The motion of the molecules from the metal move about to heat your hand- transferring the conduction.

(a) Air flows over a cold surface and is cooled by conduction (This process is termed "advective cooling.")                      
APPLICATION: California's coastal summer advection fog

 

(b) Air "sits" on a surface that gets cold overnight. (This process is termed “radiational cooling").
APPLICATION: California's Central Valley winter "tulle" or radiation fog

 

-       Expansional Cooling- the air moving over a surface of calm air.

Air expands, molecules get "further apart", do not strike each other as

often, do not "vibrate" as much. Air expands when pressure around

moving air parcels decreases markedly. Best example---air involved in

vertical motion.

APPLICATION: rising air experiences cooling at "dry adiabatic rate"

of 5.5^oF/1000 ft. This is one of the ways in which the air is cooled to

the dew point.

 

Rules of thumb:

1.     Air that rises cools because it expands as it moves upward (if the relative humidity is less than 100%, the cooling rate is 5.5^oF per 1000 ft

2.     If the air in two regions with high relative humidity is experiencing rising motion, and in one region the dew points are quite low, and in the other region they are quite high; the high dew points region will experience more precipitation.

 

 

Dew point & Latent Heat

On this link, we look at the two-pictured columns of the table. On the left is Dew Point Temperature; on the right is the Amount of Water Vapor.

-       Every increase of 10 centigrade of air parcel dew point temperature, the amount of water vapor doubles.

-       A significant source of heating is the latent heat of condensation (discussed in class). For every gram of water vapor that condenses, approximately 590 calories of "heat energy" are given to the immediate surrounding atmosphere.

- It is proven: The higher the Dew Point Temperature, the greater amount of water

vapor it holds.

 

Rules of governing winds relation to pressure system

-       Surface pressure system only

1.     Air flows counterclockwise and inward with respect to LOW PRESSURE AREAS and clockwise and outward with respect to HIGH PRESSURE AREAS.

2.     Air flows fastest the GREATER THE PRESSURE DIFFERENCE across an area (the closer the isobars).

 

- Pressure system at all levels except the surface

1.     Air flows parallel- not across, to the isobars (or height contours). They flow in a counterclockwise motion around LOW PRESSURES and clockwise around HIGH PRESSURED areas. This has to do with the Coriolis effect.

2.     Remember, air flows fastest where the GREATER PRESSURE is (or height of 1800 ft) and the DIFFERENCE of the area (the closer the isobars or height contours). 

 

Reminder:

-       Coriolis effect deflects winds to the right

-       Jet Stream: Fast flowing current of clouds, can be spotted by the closeness of isobars and short-term forecast can be made.

-       Jet Streams are called storm tracks on TV weather news. It is actually a cyclone at ground level with a rising motion connected to precipitation-it moves, so we call it a Storm Track.

-       A Polar Jet Stream is from the North and consists of the fastest, coldest air.

-       Subtropical Jet Streams are from the tropics.

 

What is Gyres?

The word Gyre comes from =Gyration=turning or twirling. The whole ocean seems to be twirling in these motions. The ocean currents that flow in the Northern Hemisphere are in a clockwise fashion, while in the Southern Hemisphere, it is a counterclockwise fashion.

 

The blue arrows indicate the position of the current; we see that the systems are both clockwise around the Pacific as well as the Atlantic currents.

The currents of the West Coast of U.S. are called the “ California Current”– North Pacific Gyres.

The current on the East Coast of U.S. is called the “Gulf Stream” – North Atlantic Gyres…these are the two massive movements.

 

 

 

-We were asked in class: “Which of the streams would you expect to be warmer?”

The Gulf Stream is warmer because of the warm current from the equator, while California stream is colder because of cold currents from North Pole.

 

* This is important to know: Because the West Coast has a colder ocean temperature, active hurricanes will never make it to California.

Reviewed The Process of Formal Publication

The professor ended the class with examples of the Formal Publication Process with visuals about his journal submissions, revisions, and letters from various people who reviewed him. Did you know that the persons who are involved in this process are all volunteers? Those who spend the time reading and revising are not paid, but respond within good timing, and helpful insights.