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Studying clouds

Overview

Clouds

Students examine the cloud cover to identify types of clouds in the sky, the amount of cloud cover, and observe and identify contrails and the amount of sky they cover.

The cloud protocols are taken directly from The GLOBE Program (www.globe.gov). Clouds can be measured as part of a more in-depth study of weather (see The GLOBE Program's Atmosphere Protocol) or as a separate activity, presented below. Observation data are entered directly into the GLOBE International site. In order to do this, you must be registered with GLOBE and use your school pass-code to access data entry.

Why study clouds?

Clouds form when air cools and water vapour present in the atmosphere condenses into water droplets or ice crystals. By observing clouds, we can get information about temperature, moisture, and wind conditions in different places in the atmosphere. Clouds play a complex role in climate. They are the source of precipitation, affect the amount of energy from the sun that reaches Earth's surface, and insulate Earth's surface and lower atmosphere. Scientists have calculated that if clouds never formed in Earth's atmosphere, the planet would be nearly 30°C higher, on average. Cloud observations play an important part in predicting future climate change.

GLOBE Canada affiliate scientist

Dr. David Hudak

Dr. David HudakDr. David Hudak is a research scientist with Environment Canada. He works in the Cloud Physics and Severe Weather Research Division at Meteorological Service of Canada.

The main focus of Dr. Hudak's work has been to observe the environment around us so as to better understand why it behaves as it does. Some day this understanding will make its way into computer models used to forecast our weather and climate. Refining these models should lead to more accurate weather forecasts and to a better understanding of our changing climate.

David began his career by obtaining an Honours Bachelor of Science in Applied Math from the University of Western Ontario. He worked as a weather forecaster with the government and also worked privately before obtaining his Ph.D. in Physics from the University of Toronto. Global work led David to weather modification experiments in Africa - a project designed to investigate the possibility of increasing rainfall through cloud seeding with aircraft - in addition to studying the monsoons in Malaysia, winter storms in Newfoundland, and blizzards in the high Arctic.

Dr. Hudak's particular field of expertise is Doppler weather radar - a network designed to improve the detection of severe weather across Canada. He is involved with field experiments across the country dealing with issues such as climate change in the Arctic and in-flight aircraft safety due to icing conditions. In 2000, Dr. Hudak was identified among the "2000 Outstanding Scientists of the 21st Century", for his contributions to radar meteorology.

As a member of the International CloudSat Science Team, Dr. Hudak is playing a key role in validating the CloudSat observations over Canada. CloudSat is a project that involves putting a radar in space on a polar orbiting satellite. This should offer unprecedented opportunities to observe the clouds and weather all across Canada. To do this, information on clouds and precipitation needs to be gathered from across the country. In northern Canada, this need is particularly acute since there is few weather observing sites available. David looks forward to working with the GLOBE Canada community to obtain this type of information and to demonstrate the usefulness of CloudSat to observing and understanding the Arctic environment.

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Purpose

To estimate the amount of cloud and contrail cover, to observe which types of clouds are visible and count the number of each type of contrail.

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Methods

Cloud types

The GLOBE protocol asks you to identify ten common types of clouds. The names used for clouds are based on 3 factors: 1. shape; 2. altitude; 3. whether producing precipitation.

  1. Three basic shapes:
    • cumulus clouds (heaped and puffy)
    • stratus clouds (layered)
    • cirrus clouds (wispy)

     
  2. Three altitude ranges: (specifically the altitude of the cloud base)
    • High clouds (> 6,000 m) = "cirrus or cirro-"
      • Cirrus
      • Cirrocumulus
      • Cirrostratus
    • Middle clouds (2,000 - 6,000 m) = "alto"
      • Altocumulus
      • Altostratus
    • Low clouds (< 2,000 m)
      • Stratus
      • Nimbostratus
      • Cumulus
      • Stratocumulus
      • Cumulonimbus

     
  3. Clouds whose names incorporate the word "nimbus" or the prefix "nimbo" - are clouds from which precipitation is falling.

Cloud identification tips:

Clouds that are wispy and high in the sky are always cirrus, of some kind. If cirrus with puffs, then they are cirrocumulus. If cirrus with layers, then cirrostratus.

Clouds at middle altitudes are designated by the prefix "alto". If in layers, they are altostratus, if in puffs they are altocumulus clouds.

Clouds forming at low altitudes (< 2,000 m) are either cumulus or stratus family.

Dark, low clouds actually producing precipitation have the designation "nimbus". Nimbostratus clouds cover the entire sky with broad sheets and produce steady rain. They are larger horizontally than vertically. Cumulonimbus clouds have dark bases and puffy tops, often anvil-shaped and are sometimes called "thunderheads." They tend to produce heavy precipitation, typically accompanied by lightning and thunder.

Contrails

Contrails are linear clouds formed around small particles in jet aircraft exhaust. These are clouds, caused directly by human activity, and are of great interest to researchers.

Contrails are distinguished by three subtypes:

  1. Short-lived contrails: obvious tail behind a plane, do not remain after plane passes;
     
  2. Persistent, non-spreading contrails: obvious contrails (linear, narrow features) that do not appear to dissipate significantly, or to show signs of spreading, and that remain long after the airplanes that created them have left the area; Each contrail subtends a narrow angle in the sky;
     
  3. Persistent, spreading contrails: obvious linear cirrus-type clouds with a diffuse appearance. Each contrail subtends a wider angle in the sky.
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Recording observations

Go to the same place each time when observing clouds, one that gives a clear view of the sky in all directions. Your cloud observation Study Site will need to be defined. To do this you will need to record measurements for latitude, longitude and elevation at the site using a GPS. Take 5 readings over 5 minutes and then average them. Name the site. You can also describe and record the Study Site as per Atmosphere Investigation Site Definition Sheet if you are using a weather station.

Cloud observations should be made within one hour of local solar noon. Solar noon is the time when the sun is at its highest point in the sky. Need help determining solar noon? Use the solar noon calculator on the GLOBE website.

You need to record local time when making cloud observations and convert this time to Universal Time for data entry. UT is displayed in the top left of the screen when you enter www.globe.gov.

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Equipment and resources

GLOBE weather chart

Data forms

Data entry

To enter your data go to the GLOBE website's data entry section. You will need a GLOBE username and password to be able to enter data onto the GLOBE website.

Links

For CloudSat, cloud activities and cloud info:

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