Highs and Lows

Solar radiation and UV

Solar radiation is the sunlight arriving on a level surface, in watts per square meter (W/m²). A clear summer noon here brings about 1,000; a low winter sun, clouds, early morning and evening bring far less, and night is zero.

UV index is the strength of the sunburning part of that light: 3 and up calls for protection, 8 and up for avoiding the midday sun.

Wind RMS and vector average

Wind RMS is the root-mean-square of the wind speeds: square each reading, average the squares, take the square root. It weighs the stronger winds more than a plain average does, so it always reads at or above the average, and the wider the gap between the two, the gustier the wind. The wind’s push on a wall or a sail grows with the square of its speed, so RMS is the steady wind that would have pushed as hard.

Vector average adds the readings as arrows: a wind that holds its direction keeps its speed, and one that swings around cancels itself out. Its direction is where the wind blew from on balance.

Evapotranspiration

Evapotranspiration (ET) is the water the ground gives back to the air: evaporation from soil and surfaces, plus what plants draw up and breathe out through their leaves.

The station estimates it from sunshine, temperature, humidity and wind, as the water a well-watered lawn would lose. Set beside rain, it tells you whether the ground is gaining water or drying out, and about how much irrigation would replace.

Solar radiation and UV

Solar radiation is the sunlight arriving on a level surface, in watts per square meter (W/m²). A clear summer noon here brings about 1,000; a low winter sun, clouds, early morning and evening bring far less, and night is zero.

UV index is the strength of the sunburning part of that light: 3 and up calls for protection, 8 and up for avoiding the midday sun.

Wind RMS and vector average

Wind RMS is the root-mean-square of the wind speeds: square each reading, average the squares, take the square root. It weighs the stronger winds more than a plain average does, so it always reads at or above the average, and the wider the gap between the two, the gustier the wind. The wind’s push on a wall or a sail grows with the square of its speed, so RMS is the steady wind that would have pushed as hard.

Vector average adds the readings as arrows: a wind that holds its direction keeps its speed, and one that swings around cancels itself out. Its direction is where the wind blew from on balance.

Evapotranspiration

Evapotranspiration (ET) is the water the ground gives back to the air: evaporation from soil and surfaces, plus what plants draw up and breathe out through their leaves.

The station estimates it from sunshine, temperature, humidity and wind, as the water a well-watered lawn would lose. Set beside rain, it tells you whether the ground is gaining water or drying out, and about how much irrigation would replace.

Solar radiation and UV

Solar radiation is the sunlight arriving on a level surface, in watts per square meter (W/m²). A clear summer noon here brings about 1,000; a low winter sun, clouds, early morning and evening bring far less, and night is zero.

UV index is the strength of the sunburning part of that light: 3 and up calls for protection, 8 and up for avoiding the midday sun.

Wind RMS and vector average

Wind RMS is the root-mean-square of the wind speeds: square each reading, average the squares, take the square root. It weighs the stronger winds more than a plain average does, so it always reads at or above the average, and the wider the gap between the two, the gustier the wind. The wind’s push on a wall or a sail grows with the square of its speed, so RMS is the steady wind that would have pushed as hard.

Vector average adds the readings as arrows: a wind that holds its direction keeps its speed, and one that swings around cancels itself out. Its direction is where the wind blew from on balance.

Evapotranspiration

Evapotranspiration (ET) is the water the ground gives back to the air: evaporation from soil and surfaces, plus what plants draw up and breathe out through their leaves.

The station estimates it from sunshine, temperature, humidity and wind, as the water a well-watered lawn would lose. Set beside rain, it tells you whether the ground is gaining water or drying out, and about how much irrigation would replace.

Solar radiation and UV

Solar radiation is the sunlight arriving on a level surface, in watts per square meter (W/m²). A clear summer noon here brings about 1,000; a low winter sun, clouds, early morning and evening bring far less, and night is zero.

UV index is the strength of the sunburning part of that light: 3 and up calls for protection, 8 and up for avoiding the midday sun.

Wind RMS and vector average

Wind RMS is the root-mean-square of the wind speeds: square each reading, average the squares, take the square root. It weighs the stronger winds more than a plain average does, so it always reads at or above the average, and the wider the gap between the two, the gustier the wind. The wind’s push on a wall or a sail grows with the square of its speed, so RMS is the steady wind that would have pushed as hard.

Vector average adds the readings as arrows: a wind that holds its direction keeps its speed, and one that swings around cancels itself out. Its direction is where the wind blew from on balance.

Evapotranspiration

Evapotranspiration (ET) is the water the ground gives back to the air: evaporation from soil and surfaces, plus what plants draw up and breathe out through their leaves.

The station estimates it from sunshine, temperature, humidity and wind, as the water a well-watered lawn would lose. Set beside rain, it tells you whether the ground is gaining water or drying out, and about how much irrigation would replace.

Solar radiation and UV

Solar radiation is the sunlight arriving on a level surface, in watts per square meter (W/m²). A clear summer noon here brings about 1,000; a low winter sun, clouds, early morning and evening bring far less, and night is zero.

UV index is the strength of the sunburning part of that light: 3 and up calls for protection, 8 and up for avoiding the midday sun.

Wind RMS and vector average

Wind RMS is the root-mean-square of the wind speeds: square each reading, average the squares, take the square root. It weighs the stronger winds more than a plain average does, so it always reads at or above the average, and the wider the gap between the two, the gustier the wind. The wind’s push on a wall or a sail grows with the square of its speed, so RMS is the steady wind that would have pushed as hard.

Vector average adds the readings as arrows: a wind that holds its direction keeps its speed, and one that swings around cancels itself out. Its direction is where the wind blew from on balance.

Evapotranspiration

Evapotranspiration (ET) is the water the ground gives back to the air: evaporation from soil and surfaces, plus what plants draw up and breathe out through their leaves.

The station estimates it from sunshine, temperature, humidity and wind, as the water a well-watered lawn would lose. Set beside rain, it tells you whether the ground is gaining water or drying out, and about how much irrigation would replace.

Solar radiation and UV

Solar radiation is the sunlight arriving on a level surface, in watts per square meter (W/m²). A clear summer noon here brings about 1,000; a low winter sun, clouds, early morning and evening bring far less, and night is zero.

UV index is the strength of the sunburning part of that light: 3 and up calls for protection, 8 and up for avoiding the midday sun.

Wind RMS and vector average

Wind RMS is the root-mean-square of the wind speeds: square each reading, average the squares, take the square root. It weighs the stronger winds more than a plain average does, so it always reads at or above the average, and the wider the gap between the two, the gustier the wind. The wind’s push on a wall or a sail grows with the square of its speed, so RMS is the steady wind that would have pushed as hard.

Vector average adds the readings as arrows: a wind that holds its direction keeps its speed, and one that swings around cancels itself out. Its direction is where the wind blew from on balance.

Evapotranspiration

Evapotranspiration (ET) is the water the ground gives back to the air: evaporation from soil and surfaces, plus what plants draw up and breathe out through their leaves.

The station estimates it from sunshine, temperature, humidity and wind, as the water a well-watered lawn would lose. Set beside rain, it tells you whether the ground is gaining water or drying out, and about how much irrigation would replace.