Three calculators for where you are on the planet and what the sky is doing there — moist-air physics, the time in another city, and how much energy a solar array will actually make.
Humidity, dew point, wet-bulb, and the full moist-air state — with a draggable psychrometric chart and a city climate atlas.
What time is it there — and when does a meeting in one city land in another? Compare cities side by side across the day.
Annualised output for a solar array — pick a city, system size, panel tilt and orientation, and see month-by-month generation.
Sunrise, sunset, day length and twilight — plus the moon phase and illumination — for any city and date.