The Origin of Weather

How uneven heating creates the atmosphere that your drone must fly through.

Think of this lesson as the origin story of weather phenomenon itself. We’re going to look at how our Sun doesn’t heat the Earth’s surface evenly—and how this singular fact sets the entire atmosphere’s ever-changing weather in motion.

We’re also going to break down how rising hot air and sinking cool air form the patterns that create wind and currents that will effect your drone’s flight and flight missions.

Finally, we’ll zoom in to see how specific surfaces like rock, pavement, or water affect flight conditions.

In the Field

Remote PIC Experiences

Imagine: You’re flying a mapping mission just outside of town. The morning air is calm, and your drone is cruising smoothly at 200 feet as it passes over farmland. The fields are still damp with dew, keeping the air above them cool and stable.

As you continue, your drone crosses into a large paved parking lot. Instantly, you notice a little bump in stability—the aircraft wobbles against a rising pocket of air. That’s an updraft in action. The blacktop has been soaking up the sun all morning, heating the surface quickly, and the air above it is now rising fast.

Moments later, you reposition the drone over a nearby pond. The effect flips. The air feels heavier and the drone dips slightly as a downdraft presses from above. The cooler water surface hasn’t warmed much at all, so the dense air sinks, pulling your drone with it.

• The Part 107 exam will test you on this principle: different surfaces, different heating, different air movements.
• In the field, knowing this helps you anticipate turbulence before it surprises your drone.

Step 1:
Uneven Heating of the Earth by Sun

All weather begins with the same source: the sun. But the sun does not heat the Earth evenly. Surfaces absorb and release heat at different rates, and this simple fact sets the entire atmosphere in motion.

• Areas near the equator (the invisible line around the middle of the planet) receive direct, concentrated sunlight.
• Regions closer to the poles get sunlight at an angle, spreading the energy over a wider area.

This uneven heating of the earth’s surface is the root cause of nearly all weather patterns.

Step 2:
Rising at the Equator, Sinking at the Poles

Once the sun’s uneven heating is in play, the atmosphere responds.

• Warm equatorial air lifts skyward while cold polar air drops, creating the first big push-and-pull that sets Earth’s air in motion.

Step 3:
Convection Currents Form

The constant looping of rising warm air and sinking cool air creates what we call convection currents. These invisible cycles are the backbone of local breezes and global circulation alike—whether it’s a light gust brushing your face or the large-scale winds that shape weather patterns worldwide.

Step 4:
Pressure Differences Form

As air rises and sinks, it directly changes the pressure felt at the Earth’s surface. Rising warm air leaves behind low-pressure zones, while sinking cool air presses down, creating high-pressure zones. These differences drive winds across the surface of the planet and form the boundaries where weather systems develop.

Step 5:
Global Circulation Begins

Once pressure differences build up across the Earth’s surface, the atmosphere starts moving on a massive scale. This movement creates global circulation patterns. These are the steady winds and weather belts that stretch across continents and oceans. These patterns are the reason trade winds, jet streams, and storm tracks exist, shaping the climate zones your drone will one day fly beneath.

Zeroing in on the Step 3: Convection Currents

When a surface warms quickly the air above it rises. When a surface stays cool the air above it sinks. This contrast creates uneven heating, which in turn produces convection currents: the consistent and ever-shifting rising and falling streams of air that drive weather.

These vertical motions cause pressure changes in the atmosphere, and that’s what gets wind and weather moving.

Remember that the primary characteristic of convection currents is vertical air movement.

Read the ground below to predict the air above.

Pilot mindset

Now that we’ve seen how the sun sets air in motion around the globe, let’s zoom into the actual surface types you’ll be flying around.

At the surface, different ground types—like pavement, water, or tree canopy—react differently to heat. And those small differences create powerful local currents that will directly and can spontaneously impact your drone’s flight stability.

Updrafts

Hot Surfaces Create Updrafts

Hard, dry surfaces like pavement, rocks, and barren soil heat up quickly under the sun. This creates localized updrafts—rising currents of air that can lift your drone or cause sudden shifts in altitude.

How it works:
As the sun hits these areas, the air above warms, gets lighter, and rises, pulling in cooler air from nearby. This rising motion is what creates an updraft.

Here’s a breakdown explained in 3 steps:

1. First, the Sun hits a hard surface → Surface heats up rapidly
2. Next, air above it gets warmer and lighter → Air rises
3. Finally, cooler air nearby moves in → Keeping the cycle going

Where Updrafts Happen:

1. Rocky Terrain
• Rocks heat up fast in the sun because they’re dry and dark. That heat warms the air right above them, which rises quickly.
• Result: Strong updrafts, especially in sunny, mountainous areas.
2. Barren Land
• Bare ground (like deserts or cleared fields) has no plants to hold moisture or shade it. The sun heats the soil quickly, warming the air and making it rise.
• Result: Consistent thermal updrafts during the hottest part of the day.
3. Urban Areas
• Pavement, rooftops, and metal surfaces soak up heat and blast it back out. Warm air rises off these surfaces, and buildings push wind upward along their sides.
• Result: Both rising heat and deflected wind can cause sudden lift—common in cities.

Downdrafts

Soft Surfaces Create Downdrafts

Cooler surfaces (like water, shaded forests, or rain-soaked ground) hold onto their chill. The air above stays denser and heavier, while nearby warmer air rushes in to replace what’s rising elsewhere. This heavier air sinks fast, creating a downdraft that can push everything below it downward.

How it works:

1. Cool surface stays shaded → Air above it stays cooler and denser
2. Nearby warmer air rushes in → Cycle continues with vertical descent
3. Heavier air begins to sink → It pushes air below it downward

Where Downdrafts Happen:

1. Bodies of Water
• Water doesn’t heat up quickly, especially before noon or after sunset. Air above stays cooler → sinks downward toward the surface.
• Result: Gentle but steady downdrafts—can reduce lift or control.
2. Dense Forests
• Thick tree cover keeps sunlight from heating the ground much. Cool, shaded air above the trees starts to fall.
• Result: Sinking air movement that can cause sluggish flight response.

3. Wet Fields & Vegetation
• Moist soil and crops hold onto water and don’t warm up fast. The air above stays heavy and drops slowly.
• Result: Low-level downdrafts, especially after rain or irrigation.

Flight Note: Downdrafts aren’t dramatic like storms, but they’re sneaky. If you’re flying low and suddenly lose altitude or power feels sluggish—check your surface. Cool terrain might be pulling your drone down.