Meteorology 302.01, Spring 2004

Class Notes for February 18, 2004

Kenny Kapoor

Rodrigo Marquez

Assignments

Homework #1 due Friday, February 20, 2004

Read Zebrowski, Up Through Chapter 2 (1-51)

Read Sheets & Williams Up Through Chapter 2

Housekeeping

- Received surface data map for February 17, 2004

Definitions

Cirrus clouds - thin, wispy clouds because they form in the higher levels of the atmosphere, usually above 18,000 feet, where little water vapor is present

Doppler Radar - the last tool meteorologists use to discern thunderstorms; the tool is capable of showing if a thunderstorm is severe or not

Cyclone - an area of low pressure completely encircled by at least one isobar

Anticyclone - an area of high pressure completely encircled by at least one isobar

Front - a boundary separating warmer air masses from colder air masses

Tropical cyclone - an atmospheric closed circulation rotating counter-clockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere

Satellite Imagery

- Reviewed comparing visible satellite imagery with infrared satellite imagery

- The clouds reflect all of the light on the sun in visible images; therefore, they do not show if any precipitation or wind is occurring

- Infrared images tend to show clouds with precipitation, except the cirrus clouds, which usually do not precipitate, but are mistaken with cumulonimbus clouds

S.F. County Severe Thunderstorm Warning

- Link to San Francisco County’s first-ever severe thunderstorm warning

- A warning is a “take action” statement

- The storm had tropical characteristics accompanied by very warm air

Pressure Features

- Reviewed pressure features on the surface data map for February 17, 2004

- Isobars have coherent or circular patterns that consist of high pressure areas and low pressure areas

-To determine if an area is low or high, a person can read the isobars on the surface data map or the pressures on the weather stations

- On a weather map, a person can identify a front when one side has warmer air systematically and the other side has colder air systematically

- Meteorologists find fronts to be very important as significant weather usually happens around fronts

500 millibar chart

- Link to weather maps from past classes

- Looked at a weather map drawn at a different pressure

- All of the weather maps we have been looking at have been observed from the ground, but a weather map taken at 18,000 feet from the ground is associated with a 500 millibar chart

- A weather balloon is sent up twice a day which observes the weather from 18,000 feet above the ground

- Winds observed 18,000 feet high tend to be stronger than when they are observed on the ground