2023-2024

Between nov 2022 and dec 2023, the air temperature on land over the littoral of Huatajata (ca 50 m from the lake) varies daily within a range of 4-20 ºC during Summer (nov-dec) as compared to 2-16 ºC during Winter (jun-jul). The values displayed are averages over 15 min periods. It s noticeable that in nov 2023 temperatures are much higher within a narrower range (10-20 ºC), than in nov 2022 (2-21 ºC). 

Air relative humidity covered a wider range in nov-dec 2022 (10-100 %) compared to feb-apr 2022 (60-95 %) much humid. It can be noticed that relative humidity was dryer and covered a narrower range in nov 2023 (20-80 %). 

The Li-COR 200R pyranometer (400-1100 nm) measures the global solar incident energy. During the 2022 Summer rainy period (nov-mar 2023) the maximum solar energy reached 1100-1200 W/m2, which are among the highest irradiance on earth. During the 2023 Winter dry period (jun-jul) the maximum only reached 600 W/m2). This seems counter-intuitive, since during the rainy period the sky is generally cloudier. As a comparison, the solar radiation is attenuated as passing through the atmosphere, leaving maximum normal surface irradiance at approximately 1000 W/m2 at sea level on a clear day. Therefore, the maximum global solar energy received at Lake Titicaca is among the highest. 

The cohesive forces between the water molecules are responsible for the phenomenon known as surface tension. For water under ambient conditions, the average surface tension is 0.072 J/m2. Water surface tension is slightly higher during the rainy period (up to 0,1 J/m2) and lower during the dry period (below 0,06 J/m2). 

In 2022, the rainy period was weak (normal intensity is historically around 5 mm/5 min), but occurred between November and April, being more intense in December. Yet, there was almost no rain occurrence starting in November 2023. Calculating the cumulative monthly precipitation is more informative. Important notice: the mechanical ran gauge has not been cleaned  in 2023, thus may be underestimating precipitation. 

The average atmospheric pressure fluctuated between 700 and 702 mbar (1 mbar = 0.75 mm Hg), thus between 525 and 526 mm Hg. With maximum of 707 mbar (530 mm Hg) and minimum of 695 mbar (521 mm Hg).  The typical pressure at sea level is 1013 mbar. With altitude the atmospheric pressure decreases. For example, at 4000 m it is only ~645 mbar. 

The quantameter LiCOR LI-190R measures the Photosynthetic Active Radiation (PAR 400-700 nm). This is the fraction of the global solar energy that micro-alga and plants use for their photosynthesis. The maximum PAR occurred during the rainy period (nov-mar) and reached 550-600 W/m2. During the dry period (jun-jul) the maximum PAR only reached 350 W/m2. 

The PAR radiation can also be expressed as a flux of photons in mol/m2/s or µE/m2/s.  Here, the maximum reached 2500-2700 mol/m2/s in nov-mar, and only 1500 mol/m2/s in jun-jul.