Dates: Tuesday, January 7th or Thursday, January 9th

Location:  Online - see your e-mail for the 

Website: https://www.weather.gov/sgx/

This week we are meeting virtually with the National Weather Service. Though it is located in Rancho Bernardo, their offices are a bit small for an in person visit for all of us. Some of you might remember our visit there all the way back in 2018; it was actually my first in-person class all by myself! Our reading is adapted from the original reading written by the incomparable Mary Burns. Bonus points if you read it originally and remember!

What is weather? What is climate?

Weather refers to the conditions in the atmosphere over a short period of  time, where climate is the weather over a long period of time.  

Weather has several variables, including humidity, precipitation, pressure,  temperature and the wind.  

Climate covers everything from the averages to the extremes of these  variables.  

Tools of Weather

As you know, there are many tools used to measure weather. They include:

• Thermometer: Measures air temperature. Most are closed glass tubes  filled with either alcohol or mercury. When the air around the tube  heats the liquid, the liquid expands and moves up the tube. When the  air contracts, it moves down. 

• Barometer: Measures air pressure. A rising barometer means sunny and dry, while a falling barometer means story and wet. 

• Sling Psychrometer: Measures relative humidity. It uses the cooling  effect of evaporation. Two thermometers are used. A wet cloth is wound around one of the psychrometers a few times. Water evaporates from the cloth, causing the temperature on that thermometer to be lower than the other.  

• Rain Gauge: Measures the amount of rain over a specific time period. • Wind Vane: Measures the direction that the wind is blowing • Anemometer: Measures wind speed. It has cups which catch the wind, and turn a dial attached to the instrument. The dial shows the speed. 

• Wind sock: A cone shaped cloth tube which indicates wind direction  and relative wind speed. 

• Weather maps: Indicate atmospheric conditions above the surface.  Weather maps are used to forecast the weather.

• Hygrometer: Measures water vapor of air or humidity.

• Weather balloon: Measures weather conditions higher in the  atmosphere. 

Weather satellites: Used to photograph and track large-scale air  movements. Computers are then used to analyze the data. 

Clouds

Clouds are  all composed of water droplets or ice crystals that float in the sky. They can  also help to predict the weather. Here are some common types of clouds and what they might predict: 

High clouds 

• Cirrus: High, delicate and feathery, mostly composed of ice crystals.  Predicts: change may be on the way. 

• Cirrostratus: thin, white and covers the sky like a veil. Most common  in winter. Predicts rain or snow within 24 hours. 

• Cirrocumulus: thin, patchy, sheet-like. Might resemble ripples.  Predicts fair but cold. However, if in a tropical region, it may predict an approaching hurricane. 

Mid-Level clouds 

• Altocumulus: Patchy white or gray layers, small rows of fluffy ripples. Predicts fair weather. 

• Altostratus: Gray or blue-gray composed of ice crystals or water.  Usually covers the entire sky. Predicts continuous rain or snow. 

• Nimbostratus: Dark, gray clouds. So thick they might block out the sun.  Predicts: Gloomy with continuous rain or snow. 

Low clouds 

• Cumulus: White, fluffy, various sizes and shapes. Predicts: Fair weather.

• Stratus: Thin, white sheets covering the whole sky. Seldom produce  much rain or snow. Predicts fair, but gloomy. 

• Cumulonimbus: Grow on hot days when warm, wet air rises high into  the sky. Predicts: Possibility of rain, hail or tornadoes. 

• Stratocumulus: Patchy gray or white clouds, honeycomb appearance.  Predicts: Fair for now, but a storm may be on the way. 

Other types of clouds 

• Contrails: Made of water droplets condensed from the water vapor in  the exhaust of jet engines. Predicts: May provide information about  the layer of moisture in the sky. 

• Mammatus: Actually altocumulus, cirrus, cumulonimbus or other  types of clouds that have pouch-like shapes hanging from the bottom.  Created when cold air within the cloud sinks towards Earth. Predicts:  Severe weather may be on the way. 

• Orographic clouds: Shaped by mountains or hills that force the air to  move over or around them. Predicts: Afternoon thunderstorms possible. 

• Lenticular clouds: Shaped like lenses, almonds or even flying saucers.  May get shape from hilly terrain or air rising over flat terrain.  Predicts: Nothing.  

Facts on climate: 

There are opinions on climate, and there are facts. The facts (which are  shown by data on the National Oceanic and Atmospheric Administration  website, climate.gov), demonstrate the following facts on climate:

• Global Average Temperature: From the 1880s (when these numbers  began to be tracked) until 1975, there was very little noticeable  change in global average temperature. But since then, there has been  a gradual trend of increasing temperature, with the average being  approximately 1° higher than 1975.  

• Carbon Dioxide in the atmosphere: Carbon dioxide in the atmosphere  has risen by 25% since 1958 (and by about 40% since the Industrial  revolution). While the level was approximately 320 ppm in 1955, it is now approximately 410 ppm. 

• Spring Snow cover: Spring snow appears to be melting earlier • Sea level: Sea level rise has grown from 1.7 mm/year (most of the  20th century) to 3.2 mm/year since 1993 

• September arctic sea ice: The arctic sea ice at the end of the summer  has shrunk by about 40% since 1979 

• Glaciers: The average thickness of 30 well-studied glaciers has  decreased more than 60 feet since 1980 

• Heat-trapping gases: The total warming effect of heat-trapping gases  has gone up by 40% since 1990, the year that many nations agreed to  cut emissions.  

• Sun’s energy: There has been no change in the energy generated by  the sun.  

Simulations are created which are based on current  figures and trends, and can project the changes over  

time if there are no other  

changes. The NOAA has  

projected a scenario of  

global temperature based  

on low growth, moderate  

growth and high growth for  

the 21st century. The image above reflects their predictions. The most dire is an increase in Global Temperature by 4 ° C. 

Videos which discuss the impact of climate change:

Types of Clouds. (2015, March 21). Retrieved from scijinks.gov: https://scijinks.gov/clouds/ 

Weather instruments. (2016, February 2). Retrieved from weatherwizkids.com: http://www.weatherwizkids.com/?page_id=82 

what is weather. (2017, February 2). Retrieved from  

learn.weatherstem.com:  

https://learn.weatherstem.com/modules/learn/lessons/148/05.html