Power systems: Weak power grid fluctuations can occur.
Spacecraft operations: Minor impact on satellite operations possible.
Other systems: Migratory animals are affected at this and higher levels;
aurora is commonly visible at high latitudes (northern Michigan and Maine).
On the ground:
Leaves and small twigs in constant motion; wind extends light flag.
On the sea:
Large wavelets. Crests begin to break. Foam of glassy appearance. Perhaps scattered white horses.
Power systems: High-latitude power systems may experience voltage alarms,
long-duration storms may cause transformer damage.
Spacecraft operations: Corrective actions to orientation may be required by ground control;
possible changes in drag affect orbit predictions.
Other systems: HF radio propagation can fade at higher latitudes,
and aurora has been seen as low as New York and Idaho (typically 55° geomagnetic latitude.).
A UV index reading of 0 to 2 means low danger from the sun's UV rays for the
average person.
Wear sunglasses on bright days. If you burn easily, cover up and use broad spectrum SPF 30+ sunscreen.
Bright surfaces, such as sand, water, and snow, will increase UV exposure.
On the ground:
Raises dust and loose paper; small branches are moved.
On the sea:
Small waves, becoming larger; fairly frequent white horses.
On the ground:
Small trees in leaf begin to sway; crested wavelets form on inland waters.
On the sea:
Moderate waves, taking a more pronounced long form; many white horses are formed.