If a METAR states "T=2•C, Td=-4•C", what do the values represent?

The values indicated in the METAR represent the temperature and the dew point. In METAR reports, "T" denotes the temperature, which is expressed in degrees Celsius (°C), and "Td" represents the dew point temperature, also measured in degrees Celsius.

In this case, "T=2•C" tells us that the current temperature at the observation station is 2 degrees Celsius, while "Td=-4•C" indicates that the dew point is at -4 degrees Celsius. These two measurements are essential for understanding the moisture content in the air. The temperature provides a general sense of the weather conditions, while the dew point gives insight into how humid or dry the air is, which can influence comfort levels and weather patterns.

The other options involve different meteorological parameters that do not relate directly to the information provided in this METAR. For example, visibility and wind pertain to how far one can see and the wind conditions, which are not mentioned here. Additionally, pressure and temperature as well as cloud cover and visibility, do not correspond to the values given in this specific METAR report. Thus, the correct interpretation of the values provided clearly identifies them as representing temperature and dew point.