Weather of the San Francisco Bay Region
by Gilliam.
Weather: How to Observe and Predict
by Dunlop.

Weather of the San Francisco Bay Region by Harold Gilliam

Weather: How to Observe and Predict the Weather by Storm Dunlop

What a delightful book, showing you where the magic of predicting the weather comes from: Simply learn that the forms of the clouds are telling you about current and future weather. Then:

The book's sections:

Weather Glossary

Glossary: A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z.


advection fog
fog formed by the horizontal movement of warm moist air over a colder surface (such as upwelled deep cold ocean water).

altocumulus (Ac).
Medium-level cumulus cloud.

altostratus (As).
Medium-level stratus cloud.

High-pressure area from which air spreads out and air in the center falls.


Changing wind direction backward from the clockwise motion of the sun (northern hemisphere) from east to north to west to south to east. Compare veering.

Beaufort wind scale
0 Under 1 Under 1 Calm Smoke rises vertically. Water mirror-flat. Becalmed.
1 1-3 1-3 Light air Smoke drifts. Small ripples on water surface. Small sailboat has just enough wind to steer by.
2 4-6 4-7 Light breeze Leaves rustle. You notice wind on your face. Wind vanes begin to move. Flags stir and wave slightly. Small wavelets with unbroken glassy crests. Wind fills small boat's sails; sailboat travels 1-2 knots.
3 7-10 8-12 Gentle breeze Leaves and twigs move. Light-weight flags extend. Crests start to break, putting some whitecaps on the wavelets. Sailboats heel; travel about 3-4 knots.
4 11-16 13-18 Moderate breeze Small branches move, raises dust, leaves and paper. Flags flap. Small waves develop, becoming longer, whitecaps. Sailboats carry all sail; good heel.
5 17-21 19-24 Fresh breeze Flags ripple. Small trees sway. Whitecaps (white-crested wavelets) and spray form. Sailboats shorten sail.
6 22-27 25-31 Strong breeze Large tree branches move. Telephone wires whistle. Umbrellas difficult to control. Flags snap and beat. Larger waves, most with whitecaps; spray. Sailboats double-reef their mainsails.
7 28-33 32-38 Near gale Large trees sway. Difficult to walk. Larger waves developing. White foam begins to be blown from breaking waves. Boats do not leave harbor; boats at sea heave too.
8 34-40 39-46 Gale Twigs and small branches break off. Difficulty walking. Moderately large waves; blown foam. Boats make for harbor.
9 41-47 47-54 Strong gale Large branches break from trees. Slight damage to buildings; tiles and shingles blown off roofs. High waves, rolling seas, dense foam. Visibility reduced by blowing spray. Argh
10 48-55 55-63 Storm Trees blown over, broken, or uprooted; considerable building damage. Large waves with overhanging crests; sea heavy and rolling and white with foam. Visibility reduced. ARGH
11 56-63 64-72 Violent Storm Extensive and widespread damage to trees and buildings. Large waves , white foam, visibility greatly reduced. ARGH!
12 Over 64 Over 73 Hurricane Extreme destruction. Sea white with foam and driving spray; negligible visibility. The rest is silence.



cirrocumulus (Cc).
High-level cumulus cloud.

cirrostratus (Cs).
High-level stratus cloud.

  1. Natural convection: bubbles of air move freely and vertically, due to the buoyancy of warmer air above cooler air.
  2. Forced convection: eddies in the air cause mixing.

Coriolis effect.
Deflection caused by the rotation of the earth; an object moving in a straight line is deflected clockwise (to the right) in the northern hemisphere; in the southern hemisphere, it is deflected counter-clockwise (to the left).

cumulonimbus (Cb).


  1. Tropical cyclone: a hurricane (self-sustaining tropical storm) with both ascending and descending air currents.
  2. Extra-tropical cyclone; a depreesion; a low-pressure area where air in the center rises.


dew point
The temperature where condensation into dew, fog, or clouds occurs in cooling air.


The process in which water turns into water vapor.





High cloud.
Bases above about 6 km. or 20,000 feet.

The amount of invisible water vapor in the air. When the air can hold no more water, it is saturated. Then it condenses as fog or cloud.


Air is cold at the surface and warms at higher elevations. This is the reverse of the normal decrease of temperature with elevation.




Low cloud.
Bases below about 2 km. or 6,500 feet.


Medium-level cloud.
Bases between about 2-to-6 km. or 6,500-to-20,000 feet.

Region above the stratosphere.


nimbostratus (Ns).






stratocumulus (Sc).

Region above the troposphere (where temperature falls with height) and below the mesosphere.
Temperature rises with height, mainly due to absortion of the sun's UV in the ozone of the stratosphere.



Air rising because its temperature is higher and density lower than that of the surrounding air.

Boundary between the troposphere (below, where temperature falls with height) and the stratosphere (above, where temperature rises with height).
Higher at the equator (16-18 km.), than the mid-latitudes (11-12 km.) and the poles (8-9 km.).
Sometimes seen in the limit of cumulonimbus tops where they are forced to spread out sideways as cirrus anvils.

Lowest region of the atmosphere; most clouds and weather occur here. Temperature tends to descend about 6°C per km.
Bounded at the top by the tropopause.



Changing wind direction in the clockwise motion of the sun (northern hemisphere) from east to south to west to north to east. Compare backing.

Fallstreaks. Trails of falling water droplets or ice crystals falling from clouds and evaporating in the sky. Their trails are often curved, as the droplets slow down as they descend and evaporate.





Links and References.

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