As altitude increases through our atmosphere, pressure steadily decreases but temperature fluctuates over a consistent and interesting pattern. That pattern defines the four logical layers of the atmosphere: the troposphere, stratosphere, mesosphere and thermosphere. Layers are also defined by where they get their energy.

The tropopause, stratopause and mesosphere form boundaries where temperature changes temporarily pause, remaining relatively constant as altitude increases.

Where we live in the troposphere, though, gets most of its energy from the ground. Temperatures decrease as altitude increases. That trend reverses in the stratosphere where the ozone layer is heated by UV radiation from the sun.Temperatures there decrease through the mesosphere as fewer and fewer molecules are there to absorb energy. Temperatures increase again through the thermosphere, where most of the Sun’s energy is absorbed.

Weather can and does occur in each of those layers and affects the layers below.

We know the most about the troposphere and stratosphere thanks in large part to nearly 900 weather balloons released world wide every 12 hours daily. We'll be learning a lot more about the mesosphere from the Atmosphere-Space Interactions Monitor (ASIM) recently deployed on the International Space Station by NASA and the European Space Agency.

Over the next two years, ASIM will monitor upper atmosphere thunderstorms with optical cameras, photometers and X- and gamma-ray detectors mounted on the outside of the Columbus Module.

From this unique platform, ASIM will observe blue jets reaching upwards through the stratosphere from the tops of thunderstorms; red sprites, electrical bursts extending into the mesosphere and elves are formed by electromagnetic pulses.

Like their weather balloon cousins below, ASIM furthers understanding of the effect of thunderstorms on Earth’s atmosphere and contributes to better atmospheric models and meteorological and climatological predictions.

“High-altitude observation allows us to study these events without the obscuring clouds,” said principal investigator Torsten Neubert of the National Space institute of the Technical University of Denmark. “This understanding can improve technology for detecting ordinary lightning.”