Power systems: Voltage corrections may be required,
false alarms triggered on some protection devices.
Spacecraft operations: Surface charging may occur on satellite components,
drag may increase on low-Earth-orbit satellites, and corrections may be needed for orientation problems.
Other systems: Intermittent satellite navigation and low-frequency radio navigation
problems may occur, HF radio may be intermittent,
and aurora has been seen as low as Illinois and Oregon (typically 50° geomagnetic latitude.).
On land:
There is a light continuous stream of wind that is felt by the face; leaves rustle; ordinary vanes moved by wind.
At Sea:
Weak and short waves in the sea, still short, but more pronounced. Crests have a glassy appearance and do not break.
Enhanced protection from UV radiation from the Sun is required. A UV index reading of 8 to 10 means very high risk of harm from unprotected sun exposure.
Take extra precautions because unprotected skin and eyes will be damaged and can burn quickly.
Minimize sun exposure between 10 a.m. and 4 p.m. If outdoors, seek shade and wear sun protective clothing,
a wide-brimmed hat, and UV-blocking sunglasses. Generously apply broad spectrum SPF 30+ sunscreen
every 2 hours, even on cloudy days, and after swimming or sweating.
Bright surfaces, such as sand, water, and snow, will increase UV exposure.
Enhanced protection from UV radiation from the Sun is required. A UV index reading of 11 or more means extreme risk of harm from unprotected sun
exposure. Take all precautions because unprotected skin and eyes can burn in minutes.
Try to avoid sun exposure between 10 a.m. and 4 p.m. If outdoors, seek shade and wear sun
protective clothing, a wide-brimmed hat, and UV-blocking sunglasses. Generously apply broad
spectrum SPF 30+ sunscreen every 2 hours, even on cloudy days, and after swimming or sweating.
Bright surfaces, such as sand, water, and snow, will increase UV exposure.
On land:
The thin branches and leaves on the trees fluctuate continuously; wind extends light flag.
At Sea:
Light and short waves are clearly visible at sea. Foam of glassy appearance. Perhaps scattered white horses.
Protection from UV radiation from the Sun is necessary. A UV index reading of 6 to 7 means high risk of harm from unprotected sun exposure.
Protection against skin and eye damage is needed.
Reduce time in the sun between 10 a.m. and 4 p.m. If outdoors,
seek shade and wear sun protective clothing, a wide-brimmed hat, and UV-blocking sunglasses.
Generously apply broad spectrum SPF 30+ sunscreen every 2 hours,
even on cloudy days, and after swimming or sweating. Bright surfaces, such as sand, water, and snow,
will increase UV exposure.
On land:
The wind picks up dust and small pieces of paper; small branches are moved.
At Sea:
The sea is moderately rough. Waves appear in the form of elongated ridges, some of which are overturned; fairly frequent white horses.
Protection from UV radiation from the Sun is necessary. A UV index reading of 3 to 5 means moderate risk of harm from unprotected sun exposure.
Stay in shade near midday when the sun is strongest. If outdoors, wear sun protective clothing,
a wide-brimmed hat, and UV-blocking sunglasses. Generously apply broad spectrum SPF 30+ sunscreen
every 2 hours, even on cloudy days, and after swimming or sweating. Bright surfaces, such as sand,
water, and snow, will increase UV exposure.
Protection from UV radiation from the Sun is not necessary. 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 land:
Direction of wind shown by smoke drift, but not by wind vanes.
At Sea:
There are very weak waves at sea. Ripples with the appearance of scales are formed, but without foam crests.