Satellite imagery stands as a cornerstone in meteorological science, offering invaluable insights into the dynamics of Earth's atmosphere. Two primary types of satellite imagery, visible and infrared, each reveal different aspects of weather patterns and atmospheric conditions. Understanding these differences is crucial for interpreting the data these images provide, especially in tracking weather phenomena like cloud thickness, snow cover, and cloud height.

Visible Satellite Imagery: This type operates on the principle of reflected visible light. The albedo, or the reflective capacity of objects, dictates their appearance in these images. Objects with a high albedo, such as snow, appear brighter because they reflect more light. Conversely, objects with a low albedo, like unfrozen bodies of water, appear darker due to their lower reflective capacity. Such imagery is particularly effective in daylight, revealing the texture and thickness of clouds and other features based on light reflection. For instance, a stationary white area across Alabama and Georgia, visible in the imagery, indicates snow cover rather than cloud movement, highlighted by the high albedo of the snow against the darker landscape.

Infrared Satellite Imagery: Unlike its visible counterpart, infrared imagery does not rely on visible light but rather on the emission of infrared radiation, which correlates with temperature. Warmer objects appear darker, and colder ones brighter. This characteristic allows meteorologists to determine cloud height and atmospheric temperatures. For example, bright clouds in infrared imagery indicate high, cold cloud tops, suggesting the presence of cirrus clouds, whereas darkly shaded clouds suggest lower, warmer clouds, such as cumulus.

The contrast between these two types of imagery is starkly evident when comparing their representations of the same geographical area. During the early morning, visible imagery may show a dark landscape that gradually brightens as the sun rises and illuminates the Earth. In contrast, infrared imagery can reveal temperature variations independent of visible light, such as the warming ground under clear skies or the varying temperatures of cloud tops.

A detailed analysis of these images can uncover nuanced details about the atmosphere. For example, clouds over the central Gulf of Mexico might appear bright in visible imagery, indicating they are somewhat thick, but appear dark in infrared, revealing their warm, low tops. Similarly, clouds over Florida that are bright in both visible and infrared imagery are likely thick, high-topped cumulonimbus clouds.

Understanding the interplay between visible and infrared satellite imagery enables meteorologists and weather enthusiasts to decipher complex atmospheric phenomena. By analyzing the albedo in visible images and temperature variations in infrared, one can track snow cover, determine cloud thickness and height, and observe the progression of weather patterns over time. This knowledge is pivotal for weather forecasting, climate research, and enhancing our understanding of the Earth's atmospheric processes.

Satellite imagery over New Zealand is primarily obtained from the geostationary satellite Himawari-8, provided courtesy of the Japanese Meteorological Agency. Visible and infrared satellite images are available at a frequency of up to every 10 minutes and show the extent of cloud coverage in a disc centred on a longitude of 140.7° E.  Additional satellite imagery can also be sourced from polar orbiting satellites, which orbit the Earth at a much lower altitude.