Skip Navigation Links 
Home About Us Contact Us
    Station List

 Data Access
    Mobile Access
    Classic Maps
    Obs Search
    Ship Obs Report
    HF Radar
    RSS Feeds Image indicating link to RSS feed access page
    Web Widget
    Web Data Guide
    Maintenance Schedule
    Station Status Report

 Program Info

    NDBC DQC Handbook


Hurricane Symbol Storm Special! View the latest observations near Atlantic Tropical Storm Peter and Atlantic Tropical Depression Seventeen.

Does air pressure vary with respect to air temperature?

Diagram of Station 42001

Lets examine some air pressure data from the Gulf of Mexico. The following data was measured at Station 42001 in the central Gulf. In January, when air temperatures average 20.7 C (69F), the average pressure is 1019.1 mb. In June, when the average air temperature is 27.6C (81.7F), the average air pressure is 1015.0 mb. As you can see, air pressure does vary according to temperature. Cold air is more dense than warm air, i.e., it weighs more. As a result, it tends to sink. Warm air, on the other hand, is less dense. Therefore, it weighs less and tends to rise. Meteorologists say that warm air is buoyant.

Beaker Image

Look at the above image. Imagine that the little circles in the beakers are air molecules. The image on the left shows the beaker of molecules when the air is cool. However, the image on the right shows the same beaker when it is warmed. As you can see, some of the molecules leave the beaker when heat is applied. The same situation occurs when the atmosphere is heated: some of the air molecules "leave" or float away, thus causing decreased air pressure.

Return to Science Education Home