Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Daytime versus Nighttime Cloud Temperature
Name: John
Status: student
Grade: 4-5
Location: NC
Country: USA
Date: N/A 


Question:
Are clouds in the day warmer then the clouds at night? Why or why not?


Replies:
Urban areas with their cover of concrete and/or asphalt are believed to cause local changes in cloud cover, relative humidity, and low level air temperature and pressure. That the effect is so large that it would affect the jet stream is a unlikely extrapolation. There are just too many other things also happening. In addition, the "natural landscape" is not inert. It too is exchanging heat energy, and light (electromagnetic radiation) with the atmosphere.

Vince Calder


John,

In general, clouds may be slightly warmer during the day than at night. However, the difference in temperature between day and night may be very small, as their temperature is more affected by the air surrounding them and physical processes that take place within the cloud (such as convection, divergence, etc., which require more of an explanation here than this question demands).

The tops of clouds are warmer in the day than during the night, simply because they're receiving energy from the Sun during the day.

Judging the warmth of the bottom and inside of the cloud during day and night is far more complicated and depends on several factors, including cloud height, cloud density, and whether you're talking about a layer of cloud or partly cloudy conditions.

Assuming that there is only one cloud layer, the height of the cloud will affect how much energy its base receives from a) solar radiation that has penetrated through the cloud, b) solar radiation that has been reflected by the ground, and c) terrestrial radiation (energy radiated by the ground). If the cloud base receives less energy from these sources at night than during the day, then it will be cooler at night. This would be normal.

During nighttime, clouds radiate energy both from their top and their base, thereby cooling overall, although the cloud base can still be warmed significantly by terrestrial energy.

If there are multiple cloud layers, the warmest one can contribute to warming the other ones, although minimally.

David R. Cook
Meteorologist
Climate Research Section
Environmental Science Division
Argonne National Laboratory



Click here to return to the Weather Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (help@newton.dep.anl.gov), or at Argonne's Educational Programs

NEWTON AND ASK A SCIENTIST
Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory