ソーラーインサイトプロ — ゴールデンアワー・日の出日の入り計算機

Latitude & Daylight at ロンドン

ロンドン sits at latitude 51.5°. At this latitude, daylight varies from approximately 16.4h in summer (solstice) to 16.4h in winter — a seasonal swing of 0.0h. The sun reaches a maximum altitude of 61.9° at summer solstice and a minimum of 15.1° at winter solstice. This high-latitude profile is what shapes ロンドン's unique sunrise, sunset, and golden hour patterns year-round.

1675年以来グリニッジ王立天文台の本拠地であるロンドンは、本初子午線——地球全体の世界時を定義する経度0度線——の発祥の地です。地球上のすべてのタイムゾーンは、テムズ川を見下ろす丘の上のこの一点を基準に測定されており、ロンドンを文字通り世界の計時の中心地としています。

Golden Hour Photography at ロンドン

Golden hour at ロンドン occurs when the sun sits between −4° and 6° above the horizon, producing soft, warm, directional light ideal for portrait and landscape photography. At ロンドン's latitude, morning golden hour typically starts in the 1–2 hours after sunrise and lasts approximately 40–70 minutes. Evening golden hour mirrors this before sunset. The longer twilight at this latitude gives photographers more time to capture the 'magic hour' compared to equatorial locations where the sun sets more steeply.

北緯51.5度に位置するロンドンでは、真夏と真冬の日照時間に8時間以上の極端な季節差があり、これが街のリズムを形作っています。6月の夏至には夕暮れが午後10時を過ぎても続き、12月の日中はわずか8時間の日照に縮まります——この幅は低緯度からの訪問者を常に驚かせます。

UV Exposure & Sun Safety at ロンドン

UV radiation at ロンドン peaks when the sun is highest in the sky — around solar noon. At 51.5° latitude, peak UV levels vary significantly by season: summer months see UV indices of 4–6 (moderate), while winter months typically register 0–1 (very low). The World Health Organization recommends sun protection when UV index exceeds 3. At ロンドン's latitude, this threshold is exceeded for approximately 4–6 months per year, making sun awareness a year-round consideration for outdoor workers and athletes.

How We Calculate Solar Data for ロンドン

All solar calculations for ロンドン use the Jean Meeus Chapter 25 solar position algorithm with bisection iteration, accurate to ±1 minute for dates between 1901–2099. Sunrise and sunset times define the moment the upper limb of the sun appears on the horizon, accounting for atmospheric refraction. Daily data is calculated client-side from ロンドン's coordinates (51.5°, -0.1°) — zero server processing means your location data never leaves your device.