Weather Math for the Outdoors: Lapse Rates, Dew Point, Cloud Base, Pressure Trends & Wind Chill

What you'll build

What you will be able to do

Each lab ends with a concrete result that you build yourself and the checker confirms, cell by cell.

• Estimate the temperature at the hut, the col and the summit from one valley reading with two textbook lapse rates, measure today's real lapse rate from two stations and use it for a better summit estimate.
• Calculate the dew point for a day of hut readings with the Magnus formula (LN), measure the dew-point spread and flag the hours when the air is close to saturation.
• Estimate the base of convective clouds from the dew-point spread, the freezing level from the valley temperature, count the days with the summit likely in cloud and let a formula name the day with the lowest base.
• Calculate the expected pressure at each point with EXP, see how a falling pressure overnight makes a barometric altimeter read too high, estimate that drift with a rule of thumb and turn a pressure reading back into an altitude with LN.
• Turn a barometer log into 3-hour changes, sort each step into the club's fictional trend classes with IFS, count the falling steps and chart the pressure curve.
• Convert wind speeds to m/s, classify them on a simplified scale with an approximate XLOOKUP, calculate the wind chill with POWER and count the readings below a fictional cold-exposure flag.
• Convert new snow into its water equivalent with IF, total the week's water, find the share that fell as snow and estimate the snowline from the freezing level.
• Turn a week of hut readings into summit temperature estimates, combine three fictional checks into one planning flag with IF and OR, count the flagged days and chart the summit wind.