Nebraska, known for its vast plains, experiences notable humidity, particularly during summer. The presence of substantial moisture in the air contributes to a distinct feeling of mugginess. Understanding the underlying scientific factors helps explain why Nebraska frequently encounters these humid conditions.
Geographic Factors
Nebraska’s geographic position plays a significant role in its humid climate. Situated in the central United States, it is relatively close to the Gulf of Mexico, a primary source of atmospheric moisture.
The absence of major mountain ranges to Nebraska’s south also contributes. No significant topographic barriers block the northward flow of moist air from the Gulf. This open landscape allows warm, humid air to move freely into Nebraska. Nebraska’s lower elevation also contributes, as humidity tends to decrease with higher altitudes, allowing for more moisture retention.
Atmospheric Influences
Dynamic atmospheric patterns deliver moisture to Nebraska. During warmer months, prevailing southerly winds consistently transport humid air northward from the Gulf of Mexico. This continuous flow acts as a conveyor belt, drawing tropical moisture directly into the region.
Maritime Tropical (mT) air masses, characterized by high temperature and substantial moisture, frequently move into Nebraska. Originating over the Gulf of Mexico and Caribbean Sea, these air masses are major contributors to humid conditions. High-pressure systems, such as the Bermuda High, can further enhance this persistent flow of moist air, effectively steering it into the central United States.
Local Contributions and Measurement
Local environmental factors also contribute to atmospheric moisture. Evaporation from Nebraska’s numerous rivers, lakes, and reservoirs releases water vapor into the air. This process contributes to localized humidity near these water bodies. Additionally, extensive agricultural practices, especially widespread irrigation, significantly influence atmospheric moisture. Crops like corn release water through evapotranspiration, often called “corn sweat,” which measurably increases local humidity.
To quantify atmospheric moisture, meteorologists use dew point rather than relative humidity. Dew point is the temperature at which air becomes saturated with water vapor; a higher dew point signifies more moisture and a muggier feel. In Nebraska, dew points frequently reach levels in the mid-60s or higher during summer, considered sticky or oppressive. The heat index, which combines air temperature with relative humidity, illustrates how the body perceives heat. High humidity hinders the body’s ability to cool itself through sweat evaporation, making high temperatures feel hotter and more uncomfortable.